First of all, I find your phrasing that he “is/was” a cop kind of interesting. Is he a cop or is he not? If he was but is no longer a cop, it could very well be that he left that career because he shares some of your same thoughts and feelings and you’re getting yourself worked up over nothing.

Anyway

To me, ACAB means that all cops are bastards collectively

It does not mean that each individual cop is a bastard.

There are undoubtedly some cops that are good people, doing their damnedest to do the right thing, standing up for the little guy against the bastards, who are trying to make the system better from the inside, who understand the role that policing should be, etc.

And there are of course some who are bastards, who abuse their power and do all of the things that make policing shitty.

And there are cops who aren’t actively bastards themselves, but also aren’t doing anything to make waves and stand up against the bastards.

It’s a case of a few rotten apples spoiling the bunch. The apple barrel has a couple absolutely amazing apples in there that are everything you could ever want from an apple, a whole bunch of meh run-of-the-mill grocery store apples, that do the job of being an apple well enough, but aren’t going to make you stand up and say “holy shit, that’s a good fucking apple,” and then there’s a handful of rotten apples that will make you puke your guts up, and unfortunately you don’t get to pick and choose which apple you’re eating, you just have to reach in blind and take a bite, and since those rotten apples are in there, it’s a pretty big gamble to make, you have to really need that apple for it to be worth it.

However, entering into a friendship is different than other interactions you’d have with the police. You get a chance to inspect the apple before you eat it, to see if it’s good, ok, or rotten to the core.

I’d say don’t dismiss him outright because he’s a cop, but try to feel him out, see what his attitude and philosophy is like, don’t grill him on it, but take note of how he reacts when different subjects are brought up, and if you find something problematic with what he says, try to explain how your views are different in a non-confrontational way, don’t make it a fight or an argument or a debate, just try to explain your thoughts and feelings and try to understand why he thinks the way he does as well. With the right people around him, it’s possible that you could help make him or keep him a good cop when otherwise he might go bad, it’s up to you if you want to take on that task.