You can block people and communities… I’m a trans woman; naziism and really just social conservatism works against me. I still think they should have a space to spout off, just as I should have a space to spout off about how irresponsible, bigoted and cruel their statements are. I also think there is nothing wrong with safe spaces; I mean look at raddle.me and on the opposite end Facebook and Twitter. Taking someone’s tounge doesn’t prove them wrong, only that you are afraid of what they have to say. The words of a fascist should be said and maybe repeated so they can be struck down by those who prefer love to hate.
I would argue that there is a line where speech becomes hate speech, in fact that line is already defined as criminal libel/defamation and assault.