A government doing something doesn't imply that it is a legitimate thing to do. It's Hume's guillotine: you can't derive an "ought" from an "is". You can't d

A government doing something doesn't imply that it is a legitimate thing to do. It's Hume's guillotine: you can't derive an "ought" from an "is". You can't derive "banning can be legitimate" (banning ought sometimes to occur) from "banning sometimes happens" (banning does sometimes occur). Taking your particular example, the mere fact that governments do ban "advocacy of genocide" doesn't mean that it's the right thing to do. If you ban "advocating genocide" then you encourage people to label everything they don't like as "advocating genocide". And look what has happened: that's what people do. For example, TRAs now sometimes claim that anyone that disagrees with their worldview (ie. disagrees with their ontological claims about sex and gender) is an advocate of genocide against them. And certainly any criticism of them at all is "hate speech", also banned in many places. I'd rather not give bad-faith actors another weapon. Bad-faith actors already twist language to get what they want. If you give them the power to twist language so that people opposing them are at risk of going to prison then the situation is very dangerous indeed. That would be my argument against banning that kind of speech. But I also think that the argument for banning it is very weak too. People might agree with it? The idea that you need to suppress certain views because people would be swayed by them otherwise, what does that say that you think of the average person? Do you really think that the average person is going to be convinced by Nazis if only they had the chance to hear from them? When I put it like that, doesn't it seem absurd? "We need to stop the Nazis from speaking because they're so damn convincing"? I think people are more likely to latch onto something that is suppressed and forbidden anyway. "The government doesn't want you to know this" is more powerful than "everyone I try to talk to about this calls me a piece of shit and doesn't want to hear a word I've got to say". Social power is much more powerful than government edicts.