I doubt that "talking" about Nazism would be illegal. It's "promoting" it that would be illegal. One also has to consider that there are other German speaking countries, like Switzerland. If this is a serious problem, rather than an imaginary one based on sombody's misunderstanding, one could create an intermediate boilerplate page containing something like the following:
Of course it is not illegal to talk about Nazism. Even "promoting" them is not illegal in most cases. But for example its illegal to lie about the holocaust or use some of (the old) symbols (for example the Hakenkreuz) for "promoting" Nazism. That means for example it is illegal to stick these symbols on you clothes.
Since Wikipedia has one rule, called NPOV, there never will be a problem with that, cause it is allowed to write "who lies about the holocaust" (we ourself would never lie about, just talking about these lies). It even is allowed to have pictures with the "Hakenkreuz" since it is allowed to show them for example in an educational context.
Ivo Köthnig