Also, I think the President is only immune from official presidential acts. So, if Trump were to hold a campaigm rally today, and omce again advocate for violence, yes, he could be sued civilly for it.Umm Clinton v. Jones said the opposite of that. The holding was that the President is NOT immune from actions that occurred prior to entering office.
If he were to do this at a presidential address? I think the suit would have to be against the government itself, not him, personally.