It is. But do you see any other cops moving to arrest the shooter? This is why people say ACAB. Sure, some of them probably really do want to make positive change, but they don't actually take the actions against other officers required to allow for that change. They instead fall in line, which makes them just another part of the problem. Law enforcement finds it more important to show a united front, even if that front is squarely against the people, and even the law itself.