Uff. I don't know about this one.
I haven't done much more research on this yet, but just on the OP and what you have said here, I'm not convinced he did anything that would quite warrant disciplinary action.
I'm not quite convinced "coming off as a confrontational asshole" in this specific context is quite enough for disciplinary action.
I can be a confrontational asshole. Let's say if I were to have a conversation with... I don't know, Ben Shapiro or whatnot, I am sure I would come off as being a dick to him, from his point of view.
This is way too subjective. All the conversations he had with various people seem to have been consensual and the issue here really fundamentally seems to be his unwillingness to change his stance, which is objectionable, but not in a way that would warrant a disciplinary action.
The guy is an asshole, but I feel the university overstepped.