No matter your political inclination, I think anyone who supports a democratic regime and the freedom it entails should be really careful on censoring and criminalizing the conduct of others. I don't think most of us need to be reminded that history basically works itself in circles, so the same strategy you know use to censor and criminalize a certain point of view, might be come to be used against you in the future.
As for punishing someone for threats of violence. That's what the doctrine calls crimes of abstract danger. Or, in the German Crimnal Law, abstrakt Gefährdungsdelikte. It comes from the fallacious, outdated notion of a victimless crime and restraining the freedom of someone based on the presumption of danger. One would think the Grundgesetz should protect people against the barbaric notion of punishment against abstract danger, but it is long since the Grundgesetz stopped being a warranty against the arbitrariness of Government to become a tool of its ideological inclinations. Basically making the mistake I pointed out on my first paragraph.
What Germany needs, if it wants to still be called a land of democratic rule of law, and remind people of the dangers of an unchecked nation against a minority, is better politics of memory, not punishment, because that's counterproductive at least, and can even be considered downright incoherent and paradoxal. I've written elsewhere once on how the politics of memory on Germany are all about WW2 guilt to the point of being psychological terrorism instead of a reasonable discussion on the limits of State. On other words, ein totales Scheiß.