Selective enforcement can be a thing, sure, but there's no such thing as selective believing, at least on the part of the immigrants in this scenario. And by that, I mean, sure, Trump can say behind closed doors he won't raid the chicken plant, or the hog farm, or the state of Florida, but what he can't do is go on TV and say "Listen, we're not going to target illegals that work in x, y, and z industry." So guess who isn't still going to show up for fucking work? Or guess who's going to get arrested in their homes instead of at work?
And another thing to consider is Trump is 82, and he's succesfully avoided jail. If he doesn't die in office, he's already safe, and that's if we don't "elect" him again for a third term. This guy doesn't need campaign donations anymore. He probably doesn't care about them. And what would someone do, try to report that they bribed Trump but he didn't follow through? He's untouchable at this point save the hand of another Luigi.