The word “Master Race” is clearly equivalent to terms which were used by Nazis and so are today’s far right wing and alt-rights.
There are other communities which created similar narratives, especially from the 4chan side, and I think the origin of “PC Master Race” comes from there.
Thank you OP, for your important comment! The unthinking use of Nazi vocabulary only unnecessarily reproduces their rhetoric. It’s not about language policing, it’s about knowledge of history, a sense of appropriateness and style of language. Unfortunately, most people here don’t want to deal with this, yet it is an important part of “Never Again.” Unfortunately, the U.S. is running blindly into a new fascism, and language in particular is a catalyst. It helps the fascists push the boundaries of what can be said (and maybe done).