In part, that is a problem that I have with the legal theory. Normally, unless it rises to conspiracy under the law, mere encouragement isn’t enough for liability. It’s akin to the statement that collusion isn’t a crime.
Now, turning from a legal analysis to a policy one, we have no disagreement on the issue of indoctrination and infantalization (is that a word?) of students at colleges and universities. I just saw it in action in fact. My son’s undergrad thesis presentation was on the ordinary German lawyer and judge and the Holocaust. An interesting topic and it got a good audience. One of the faculty tried to turn it into an anti trump diatribe. Now you know how I feel about Orange, but that was completely not the topic at hand. I would have said something but didn’t want his grade to be impacted.
My point though is a legal one. When does encouragement in the speech realm produce liability? It’s an interesting and difficult subject.