If it really is entrapment, a judge can toss out the testimony.

In a just world. This would indeed be the case. As I stated elsewhere it is not just. People clearly guilty walk free often these days, and others face harsh sentences when they shouldn't. There is not an equal application of the law.

If they get a judge who actually honors their oaths and respects the law then you are correct. Yet there are plenty that do not.

All we need do is look at all the judges making rulings about DACA when DACA is not a law, a bill, or anything that those judges actually have the authority to rule upon since it was just the MEMO from the head of Homeland Security stating they were not going to enforce the immigration laws, along with some Obama actions(not even a signed executive action). Yet it is not a law, and it is not a bill. We still have judges who seem to think they have the authority to rule upon those things.