People have been getting mad at him fort every video since fnaf. The problem is that they keep getting mad at him for the wrong reasons. Usually its “oh it’s because he claimed all his theories are Canon” which can’t be farther from the truth since he ends each video with “but hey that’s just a theory”
It was especially prevalent in the sans theory because a much better reason would be “because occams razor dictates its probably something else and also frisk would not recognize him as sans of he had skin”
Here though, people are taking it out of context. He chose that game for a specific reason and was there because he was chosen to represent a culture.