Had Hitler not been imprisoned and seemingly "martyred" for his beliefs, he wouldn't have written Mein Kampf, and the Nazi party, unable to find a martyr to rally behind would slowly fade away ...
Agreed. Henceforth, we shall stop imprisoning people who do bad things, lest they become martyrs to the cause for which they were imprisoned, thus creating a fascist movement dedicated to (murder/rape/jaywalking). Indeed, we should instead imprison those who do GOOD things, creating martyrs who will inspire virtue in the populace! And all men shall walk on the water, and swim upon the land. Huzzah!
In other news, your historical counterfactual is ridiculously overstated, as is the argument it tries to support. Look, I'm not an advocate of censorship, but I understand its appeal to Germans, who understand fascism and the cultural forces giving rise to a bit better than, I daresay, you seem to. America today is much closer to fascism than Germany, despite the wonderful (I mean that sincerely) protections for speech afforded by the US constitution.
Note also that this story is not about government censorship, but about some guys running a website that shows you ads and sells your personal information in exchange for letting you talk to your friends and post pictures of your boobs. As The Dude would say: this isn't a First Amendment thing, Walter.