Yes, Fuentes is a troll more than a real anti-Semite. But if that is where he wants to dance, then he wears the label.
Trump gets Secret Service protection and they screen who he is going to meet with. The fact that Trump does not have one person working with the SS to see people's backgrounds indicates a real problem.
I think a certain number of Trumps secret service want Trump to fail and fail in ways great and small. These people are likely to be embedded by Never Trumps or GOPe.