Free speech means people can say what they thing, even if you disagree with them. And it should be protected at all costs. Threats are a totally different matter. Lynching did not and does not results from free speech, quite the contrary. And by censoring people you don’t agree with, you’re not only giving up one of the most important core freedoms of your democracy, you’re also giving nazis and the like more attention and legitimacy than they would get otherwise. You’re actually helping their cause.