It is well established that the federal government has complete control over immigration. See especially Arizona v. US which holds that
States are precluded from regulating conduct in a field that Congress
has determined must be regulated by its exclusive governance.
De Canas v. Bica (1976), 424 U.S. 351 is also relevant to the application of field preemption to INA. In this case, the courts found that Congress had not (at that point) entered the field of employment of unauthorized workers, so state laws were not preempted by federal law. Laws can change, and with them, potential state powers.
In Arizona the court held that
Intent can be inferred from a framework of regulation “so pervasive .
. . that Congress left no room for the States to supplement it” or
where a “federal interest is so dominant that the federal system will
be assumed to preclude enforcement of state laws on the same subject”
and with respect to issues of immigration,
Because Congress has occupied the field, even complementary state
regulation is impermissible.
The Immigration Reform and Control Act of 1986 adds provisions to the Immigration and Nationality Act, including employment-related law, thus Congress has entered the field of regulating immigration with respect to employment. Current 8 USC §1324b arises from various amendments to the INA, where the present expression "protected individual" was inserted, by Public Law 101-649, to replace earlier "citizen or intended citizen". Congress also introduced Temporary Protected Status in §302 of the law, which has specific (more restricted) provisions regarding employment.
The evidence clearly indicates that Congress intended to include employment issues w.r.t. their supreme power regarding immigration. These discrimination provisions are in the field of immigration, and not discrimination legislation (where Congress has not preempted the field). Congressional silence must, in the light of what Congress did say, be interpreted to mean that the US immigration policy only offers certain specific protections, and states cannot add to or subtract from those protections.