If you work alongside bastards, like civil-rights-violating bastards not chew-with-your-mouth-open bastards, and aren’t actively working to get them removed from the force - i’ve got bad news about your bastard status.
Which is the point of the saying. It’s not that all cops are individually bastardly, it’s that all cops are part of a system that both protects bastards regularly, and does systemically bastardly things (like say heavily policing crimes of poverty while ignoring crimes of wealth).
I'd have to go through a decent chunk of the dictionary before I started referring to people who chew with their mouth open as "bastards."
> systemically bastardly things (like say heavily policing crimes of poverty while ignoring crimes of wealth)
I'm the last person I would expect to be defending police, but I think if you look at the rate of physical and property violence perpetrated by "crimes of poverty" vs. "crimes of wealth" that might have a lot more to do with it than the cop trying to decide if the victim has money or not before they do anything.