It is true that 18 USC 2384 reads:
If two or more persons in any State or Territory, or in any place subject to the jurisdiction of the United States, conspire to overthrow, put down, or to destroy by force the Government of the United States, or to levy war against them, or to oppose by force the authority thereof, or by force to prevent, hinder, or delay the execution of any law of the United States, or by force to seize, take, or possess any property of the United States contrary to the authority thereof, they shall each be fined under this title or imprisoned not more than twenty years, or both.
The clause making it a crime to "by force ... possess any property of the United States contrary to the authority thereof" was probably intended to refer to the forcible seizure of forts and armories, not automobiles or wagons. One must recall that this statute was originally passed in response to the outbreak of the US Civil War in 1861, and particularly in response to the forceful seizure of Fort Sumter and many other Federal military posts. While a literal reading of this clause would imply that any theft of Federal Government Property done by two or mote people using force would fall under this statute, a court is not likely to overlook this history, nor the title "Seditious conspiracy". Mere forceful theft of government property cannot reasonably be construed as an attempt to put down, overthrow, or oppode thje authority of the government.
Use of Section 2384
Section 2384 has not been frequently used, and has surely not been used to prosecute ordinarly theft of government property. As then Lawfare article "Seditious Conspiracy: What to Make of the Latest Oath Keepers Indictment" (January 14, 2022) states:
... seditious conspiracy remains an exceptionally serious, and rarely prosecuted, criminal offense because of its expressive effect. To label something sedition goes beyond normal criminality, suggesting that the conduct strikes at the heart of American democracy and falls within the same conceptual category as the most serious political crimes, such as rebellion, insurrection and treason.
As its name suggests, seditious conspiracy, the main charge, requires the government to establish both the existence of a conspiracy and that its aim was sedition. To satisfy the former, the standard elements of conspiracy apply: an agreement between multiple people to commit some unlawful act. ...
What makes seditious conspiracy special—and a rarely invoked offense—is the sedition part. Specifically, under Section 2384, individuals have committed sedition when they “conspire to overthrow, put down, or to destroy by force the Government of the United States … or to oppose by force the authority thereof, or by force to prevent, hinder, or delay the execution of any law of the United States, or by force to seize, take, or possess any property of the United States contrary to the authority thereof.” While the facts alleged in the indictment could plausibly be characterized as opposing by force the authority of the U.S. government, the indictment alleges the broader formulation of sedition: the use of force to prevent, hinder or delay the execution of a law—specifically, the constitutional and statutory provisions surrounding the transfer of power after a presidential election.
Importantly, the alleged conduct at issue avoids the problem the government faced during the most recent seditious conspiracy prosecution: the failed attempt to prosecute members of the Christian military “Hutaree” group in Michigan, which sought to kill a police officer so as to provoke a “more wide-spread uprising against the Government.” In that case, the district court threw out the seditious conspiracy charge because, while the Hutarees were plotting to attack government officials, they were not planning to “forcibly resist a positive show of authority by the Federal Government.”
This reasoning seems to suggest that a prosecution for violation of Section 2384 cannot be maintained unless there is proof that the conspiracy was in fact seditious, that is, was aimed at the overthrow of, or direct forcible opposition to, the United States Government. That would certainly not be the case for a prosecution for a conspiracy to steal government property, without more.
Another Lawfare article "The Last Time the Justice Department Prosecuted a Seditious Conspiracy Case" (February 24, 2021) states:
Why should anyone care about the Hutaree now? Because one of those serious charges was seditious conspiracy under 18 U.S.C. § 2384. It was the last time the Justice Department would use the statute until the present day. And the fate of the Hutaree may offer some insight into why. The judge in the case threw out the seditious conspiracy charges, along with the other more serious charges on the docket. And in the end, three Hutaree members pleaded guilty to standard-fare federal weapons charges.
... the seditious conspiracy charge is a genuine rarity on federal criminal dockets. Before the Hutaree case, the Justice Department had brought seditious conspiracy charges only three times in the previous 20 years: twice for small U.S. al-Qaeda cells and once for the Blind Sheikh and other al-Qaeda operatives responsible for the 1993 World Trade Center bombing and a planned spree of terror attacks around the New York area.
Judge Roberts put an end to the case five days after the government wrapped its presentation of evidence. She dismissed all charges against five of the seven defendants and tabled all charges against Stone and his son except for the more mundane weapons charges, to which the pair later pleaded guilty and got sentenced to time served.
Roberts foregrounds her acquittal order by emphasizing the case law standards to prove conspiracy charges, seditious or otherwise. She invokes a Seventh Circuit ruling stemming from an appeal of the Chicago Seven conspiracy verdict. That panel held that in cases concerning “group activity” that falls “within the shadow of the first amendment,” the court ought to undertake a “[s]pecially meticulous inquiry into the sufficiency of proof.” The government’s case against the Hutaree relied largely on Stone’s whacky speeches, so Roberts emphasizes that she “takes particular care” to scrutinize the government’s case against each defendant. She also points to United States v. Lee, a 1993 case from the U.S. Court of Appeals for the Sixth Circuit, which lays out a three-pronged test required for conspiracy cases. Per Lee, the government has to prove that everyone named in the conspiracy “shared a ‘unity of purpose,’ the intent to achieve a common goal, and an agreement to work toward that goal.” And she notes that the 1944 Fifth Circuit case Pinkerton v. United States outlines a standard with particular relevance to the Hutaree case: “a conspiracy requires a specific plan.” Never mind seditious conspiracy, Roberts declares that “the Government did not provide sufficient proof of the existence of any conspiracy at all.”
U.S. v. Lee
In U.S. v. Lee 991 F.2d 343 (6th Cir. 1993) the Sixth Circuit court wrote:
The essential elements of the crime of conspiracy are:
(1) that the conspiracy described in the indictment was willfully formed, and was existing at or about the time alleged; (2) that the accused willfully became a member of the conspiracy; (3) that one of the conspirators thereafter knowingly committed at least one of the overt acts charged in the indictment, at or about the time and place alleged; and (4) that such overt act was knowingly done in furtherance of some object or purpose of the conspiracy as charged.
United States v. Poulos, 895 F.2d 1113, 1117 (6th Cir. 1990) (quoting United States v. Meyers, 646 F.2d 1142, 1143-44 (6th Cir. 1981)). More specifically, to sustain a conviction under 21 U.S.C. § 846, the government is required to prove the existence of an agreement to violate the drug laws and that each conspirator knew of, intended to join, and participated in the conspiracy. United States v. Sanchez, 928 F.2d 1450, 1457 (6th Cir. 1991).
... A defendant cannot be convicted of conspiracy merely on the grounds of guilt by association, and mere association with the members of a conspiracy without the intention and agreement to accomplish an illegal objective is not sufficient to make an individual a conspirator. See United States v. Melchor-Lopez, 627 F.2d 886, 891 (9th Cir. 1980).
If an indictment alleges one conspiracy, but the evidence can be construed as only supporting a finding of multiple conspiracies, a variance results. United States v. Warner, 690 F.2d 545, 548 (6th Cir. 1982). However, even if a variance exists, it does not constitute reversible error "unless it prejudice[s] [the defendant's] substantial rights."* United States v. Guerra-Marez*, 928 F.2d 665, 671 (5th Cir.), cert. denied, ___ U.S. ___, 112 S.Ct. 322, 116 L.Ed.2d 263 and ___ U.S. ___, 112 S.Ct. 443, 116 L.Ed.2d 461 (1991) (quoting United States v. Richerson, 833 F.2d 1147, 1154-55 (5th Cir. 1987)). Moreover, "[i]f the government proves multiple conspiracies and a defendant's involvement in at least one of them, then clearly there is no variance affecting that defendant's substantial rights." Guerra-Marez, 928 F.2d at 672 (quoting United States v. L'Hoste, 609 F.2d 796, 801 (5th Cir.), cert. denied, 449 U.S. 833, 101 S.Ct. 104, 66 L.Ed.2d 39 (1980)).
So ther elements of a general conspiracy must be proved for a lawful conviction of a seditious conspiracy.
As far as I can learn, the US DoJ has never brought seditious conspiracy charges against people accused merely of stealing government property. Rather it has reserved such charges for people accused of seriously attempting to organize a revolt, or a violent armed opposition to the government as a whole, or a significant part of that government. Should a charge under Sec 2384 be brought for a simple case of theft by force of government property, we will then see how a court handles the issue. But it seems unlikely that such a charge will be brought, and no such charge has been brought in the current prosecution under 2384.