Kim telling you you are fucking stupid, which is good enough.

One of the other questlines ends with the government disappearing you. That Kim can barely muster up some disagreement is not good enough. The fascist playthrough is such a great showing of "there are no good cops". And when I say fascist I don't just mean the ideological quest, I mean playing the game as a fascist piece of shit.

I'm mainly paraphrasing some long essay I read about it a while ago, but that's the point - Kim calls you out, but he doesn't change anything. He's basically the guy looking on sadly as the other cop chokes out George Floyd. Marginally better. I'll see if I can find it, it's really thought provoking.

Same with rolling his eyes over you becoming racist, but, at least you are helpful?

Rolling your eyes at your racist colleague does nothing. Letting your racist colleague spend three days being a drunken oaf and not stepping in...
He wouldn't have to drop the case, he could reach out to either precinct about your massive misconduct. Instead he will support you, pay your rent and so on - when he could have gotten someone else sent out instead... These things are indictments. He will shake his head, he will tell you off, but that's all he will do. He'll still stand by your side.
Kim is only as good as you are. If you play a "realistic" cop, then he is shown for the moralist that he is - or can be, depending on the story.

I personally have a lot of faith in the games writing, so that when he doesn't stop you from killing cunoesse or doesn't give you a game over elsewhere, that's not an accident. That's on purpose. Shooting cunoesse is a game over, it could just as easily have ended with Kim stepping in.

I haven't done the fascist playthrough, but I heard Kim ends that quest by telling you that you're fucking stupid, which is good enough

Is it though? That's like a fascist complaining their partner is a dumb kind of fascist.

Sure. I personally read him as intended to convey that even the "good cops" are bastards. I'm personally of the philosophy that things don't need to be handed to the player/reader/etc on a plate—depending on the degree to which you agree, one might think that Kim should've been more clearly/explicitly a bastard, but like, imo the game is from a cop's pov and from the pov of a character who has a good relationship with Kim, and what the game does with writing him as a bastard whilst still being personally likeable from the pov of the protagonist is well-done.