Well, I didn't expect my very first question ever on this site to hit the Hot Network questions and in the meantime, I know that the concept of an unspeakable term is foreign to German culture and that is why I accepted the answer rather quickly.
However, I disagree with the opinion-based close reason the question now has, because I've been contacted through IM by various friends on the SE network with a bit more background, and I've been shown German law is quite clear: For educational and historical purposes, any speech is allowed ¹ so I would definitely not call that opinion-based.
And thanks again for everyone giving balanced answers: learning a language is learning more than just a language: It's also learning about the culture!
Note ¹: Which does not mean you should go skipping down the street singing the words in section 3.2.2. Parolen und Grußformen of the law, because that is indeed, Verboten and rightly so as it serves no purpose whatsoever.