I believe it trivializes the movement because it injects unimportant issues like git branch names into the realm of conversations about racism, police violence, harmful stereotypes, discrimination etc. It also gives ammunition to those who seek to discredit the movement for social justice. This isn't a situation like e.g. affirmative action, which demonstrably creates opportunities for minorities at the cost of some resentment from people who feel like affirmative action is unfair. In the case of "master" to "main", nobody gains anything, all it does is act is a flashpoint for bad faith actors.