Non-violent does not mean his only action was “kindness.” Read his letter from Birmingham Jail. He was a passionate, and sometimes angry man who had a lot to say about moderate white liberals who used tone arguments and told black people to calm down and be patient for their rights. He even argued that moderate whites were WORSE than blatant racists, because they cloak their bigotry in tone policing rhetoric.
He organized marches, demonstrations, boycotts. He spoke strongly and passionately, and he was not above condemning racists and calling out racism around him loudly, and it landed him in jail. It ended up getting him shot.
He may have been much more assimilist than Malcolm X was, but that doesn’t mean he operated solely through “being nice to white people.”
MLK is not your polite little talking head, preaching about how you get equality through please and thank yous.