We should all care about police killing unarmed civilians. We are paying police officers' salaries, and as such we should expect them to earn those salaries by not killing innocent people sleeping in their beds or people who maybe committed misdemeanors. Last I checked we weren't paying police officers to be judge, jury and executioner. So if you care about the Constitution you ought to care about the main goal of the Black Lives Matter movement, which is to hold police accountable for police brutality and killings of unarmed civilians. I'm not going to bother to get into the weeds of your other argument, because I'm not in the mood to have a huge headache.