Local Mexican food chain owner keeps cc tips.

I live in Oregon and frequent a taco truck near my work. It has come to my attention that the owner of said taco truck keeps all credit card tips. And knows he can get away with it because he only hires undocumented immigrants. I’ve made it a point to not only tip cash but to let everyone else I can know to also tip in cash. Would it be possible to report this without the risk of these amazing hard workers getting deported?