That's a pretty broad brush. I attended Cal and observed a sizable Anarchist population in Berkeley and Oakland that actually had nothing to do with the University. Were some of the rioters from Cal? Probably. I suspect the vast majority were not.

At least at the University level it seems like free speech was an important factor for deciding to allow hosting somebody with such an incendiary message. Here's the chancellor's statement: http://news.berkeley.edu/2017/01/26/chancellor-statement-on-...