I disagree with these sort of bans on speech as well, and it has never been because I naively believe that the speech is harmless. It is because I believe that granting the government the authority to pick and choose which speech is harmful is far more dangerous, and prone to abuse. It is because I think it is beneficial for reasonable members of the public to be able to see what garbage the other side is being indoctrinated with. It is because I believe that the portion of the public who is mostly likely to believe the harmful speech will see the censorship as more proof that they should. Most importantly it is because I believe that sheltering people from harmful ideas might protect them in the short term, but won't prepare them to deal with the seductiveness of harmful ideas that sound right when they do slip through.