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.
Ok, my mistake, but does this change the fact that the term still characterizes structural racism? Also, due to the nature of anonymity, we cannot know much about the motivations of any particular person on the internet. 4chan and alt right are exactly where you least expect them to be.