Don't let him speak? Threaten to remove Columbia's funding because they let him talk? What country are we in again?
When he's Over There, he can pick and choose what he answers. The european media isn't exactly super tough on him either, it's only when he came here that he got the hard questions.
Keep your friends close and your enemies closer. Refusing to allow him to talk plays into his hands and serves the interests of those internationally who would see our country harmed, because they can tell whatever story they want without risk of being contradicted.