Although Kaepernick as an American citizen has a right not to salute the flag, his choice sets a bad example and is inappropriate. I agree that violence and other forms of bullying by police against civilians is a huge issue that those in power don't care about. I also agree that it disproportionately affects blacks. But it's a problem for all of us. Just because it disproportionately affects blacks does not make it a racial issue, or make the USA pro-white.
Kaepernick may not be a bad American. But by his actions he looks like one now. If he wants to play pro ball, he should apologize publicly for his actions and change how he chooses to represent himself and his team.