I'm not being judgemental, I entirely get your point. The way a lot of people see it, me semi-included, is that a good person choosing to work within and support a bad system kind of takes away from their goodness. It's like the saying that there are no good millionaires, because if they were really good they wouldn't hoard enough money to become a millionaire in the first place; they'd give it away.

I don't think your BIL is a bad person for being a cop, but there's a lot of nuance.