The flag and anthem does not represent the military. It represents the country as a whole, including the military. He was protesting social injustice, not just police brutality. Social injustice is an issue that affects the entire country, so it was appropriate to protest at this time. He was not the first to protest during the National Anthem, and he wont be the last. The only reason people believed it was against the military is because a certain president claimed that it was.
Oh good, the dumbass kneeling controversy that I loved hearing about so much.
How anyone could give MORE of a fug about the anthem, the flyover, the fuging halftime show or whatever NON-football related thing that happens during the game is a mystery to me. You could get rid of every single solitary one of those things and I'd still watch because I actually like football. What a crazy concept, I know.