I would take someone, not in the abstract, planning to violently overthrow the government, as being unprotected free speech.
Leaving aside the fact that you take it wrongly, why even mention anyone "attending speeches" if his intent is 'only' to arrest those giving the speeches? "(S)omeone attending speeches" ought never have been brought up if Paul's intent is only to clamp down on those actually doing the speechifying, which is pretty self-evidently not the case from the quotation in question.
He might be saying, we should be taking action against people that actively propose overthrowing the government, and we should look carefully at the associates of those people. And yet, I think it is fine to look at "known contacts" of people (this from a guy who had dinner with a DA last week).