There are plenty of people who think the vast majority of the police are public servants trying to do their job, serve and protect. Maybe they're right. Some are. I've had good interactions with police officers and bad ones. The author was trying to do the right thing and maybe save someone's life. If a woman screams for help in a dark alley, it isn't common sense to run in and try to help her -- you're putting yourself in the line of fire. But it's brave and we celebrate and worship the people who do it rightfully as heroes, we don't berate them for "not having common sense" and putting themselves at risk.
What he did took courage or naive ignorance (or both) and from the rest of the article I'm fairly certain it's not ignorance -- he's well aware of rampant police brutality.