Why are you quoting a Tea Party "law" teacher which happens to be one of the biggest idiots of the law world?
He's not agreeing with him, he's pointing out how funny it is that Volokh claimed that the students cannot be expelled, right before they were in fact expelled.
That doesn't really prove anything. The students in Tinker vs. Des Moines and their lawyers alleged that they couldn't be suspended, but the school suspended them. Then the Supreme Court agreed that they were right. We're only at stage two here.
Like I said, it really all depends on what the student code of conduct that they signed says.