An understandable situation. But by admitting this, your company is admitting liability for citizenship discrimination (8 U.S.C. § 1324b).
Even though you are not submitting a PERM and running into potential issues with fraud there, the underlying act of rejecting US citizen/LPR applicants is the same, so I don't see how this would be any different than, for example, the Apple case last year (https://www.justice.gov/opa/pr/justice-department-secures-25...) with a $25M settlement.
In the Apple case, the company did actually obtain PERMs for some of the positions, but they were only charged with discrimination against the un-hired applications, not anything to do with the the hiring/sponsoring of the foreign workers. Furthermore, the case did not even allege actual tossing out of US citizen resumes, but merely making the applications deliberately inconvenient to avoid actually receiving any unwanted "real" applications.