The I-134 is not legally binding.
From the State Department's Foreign Affairs Manual, 9 FAM 302.8-2(B)(2)(f)(3)(a):
Nevertheless, there still are circumstances when Form I-134 will be
beneficial. This affidavit, submitted by the applicant at your
request, is not legally binding on the sponsor and should not be
accorded the same weight as Form I-864.
From USCIS's Adjudicator's Field Manual, Chapter 30.8, the section on I-134s:
Such affidavits, although helpful in judging financial ability, are
not legally binding.
Here is a federal district court opinion that confirms I-134 is not legally binding, and cites several legal precedents to support this (page 10-11):
C. Affidavit of Support
Zirintusa asserts that Whitaker breached the Affidavit of Support
(Form I-134) submitted to the INS, in which Whitaker promised to
provide room, board, and tuition to Zirintusa for a period of three
years. Whitaker argues that the Affidavit of Support is not a binding
contract between the parties. Federal Courts have repeatedly sided
with Whitaker. See, e.g., Cheshire v. Cheshire, No.
3:05-CV-00453-TJC-MCR, 2006 WL 1208010, at *2 (M.D. Fla. May 4, 2006)
(“[F]ederal courts have consistently found that Form I-134 is not a
legally enforceable contract against a sponsor by a sponsored
immigrant.”); Stump v. Stump, No. 1:04-CV-253-TS, 2005 WL 1290658,
at *4 (N.D. Ind. May 27, Case 1:05-cv-01738-EGS Document 39
Filed 01/03/07 Page 10 of 20 11 2005) (finding that the I-134 Form
“is a nonenforceable promise by the sponsor to support the alien”);
Tornheim v. Kohn, No. 00 CV 5084(SJ), 2002 WL 482534, at *4 (E.D.N.Y. Mar, 26, 2002) (“[A]n affidavit of support on an I-134 Form
is not a legally binding contract.”). The Court sees no reason to
disagree with the holdings of these courts. Thus, the Court grants
Whitaker’s motion for judgment on the pleadings as to Zirintusa’s
claim for breach of the Affidavit of Support.