That analysis sounds as if it ought to be right, that there are some things so terrible that you can't let them sit out there. But the problem with it is that the Weimar Republic--Germany for the 12 years before the Nazi Party came to power--had its own version of section 13 and equivalent laws. It was very much a kind of proto-Canada in its hate speech laws.
The Nazi Party had 200 prosecutions brought against it for anti-Semitic speech. At one point the State of Bavaria issued an order banning Hitler from giving public speeches. But all it did, as Ezra said, was glamorize him and make him a hero: “What is he saying that is so dangerous the state won't permit him to say it?” If Hitler came back today--I don't know where he is; he's 128 years old and living in the South American jungles, or wherever--but if he came back today he would laugh his head off at the anti-Holocaust denial laws in Europe, because it would show that his ideas were still powerful and dangerous.
The lesson we should learn from Germany is that for the 12 years before Hitler came to power it had all the hate-speech laws and section 13 laws in the world, but they did nothing but glamorize Adolf Hitler and the Nazis and facilitate his rise to power.