I suppose most of us have unknowingly “hired” illegals along the way, via subcontractors. It happens, especially if we’re in a distant location and don’t control or notice who shows up to push a broom at a job site.
We’ve built in CA. It would surprise me if some of the contractors and subs HADN’T hired illegals.
And as I said up thread, sometimes its just easier to pay a fine than fight it; so he did.