Make a fictional character suddenly change race when their race plays zero importance in the back story, and white people complain unless said character suddenly becomes white. Any such things to make a person colored will be met with fierce claims of sjws and political correctness.
Heck, white people get so angry about stuff that when the media reports on crimes, they'll show the mug shots of people of color, or if they died then any pictures of them looking mean plus dig up dirt on them. Yet a white person committing horrible crimes gets them either labeled Muslim, or they'll have their pictures of them surrounded by family being happy (even if they murdered the family).
Not that this is my belief, but let's play devil's advocate: if a movie had a black character as the main one initially, and it was changed to a white person, do you think there would be no controversy? I feel like your first point would apply to both sides of this argument.
Yeah, the level of the responses make the response from black people insignificant in comparison. ---