It makes sense to me, although I'm not sure I can articulate how. What I'm impressed with is how well they incorporate human instinct as a gameplay mechanic. Knowing cops like I do it's totally believable to me that they would recognize one of their own, whether they're in uniform or not. And when they see a guy who doesn't belong in said uniform -- well, it's like they just know somehow. It's a nebulous thing to try to explain over the internet, yet I'm pretty sure everyone is familiar with the concept on some level.
Something else I wanted to point out; "when you've found so what seems like the biggest weed farm in the city would you really drop everything else to pursue someone who you think might not be a cop?" A cop would definitely be interested in that, yes. That much contraband and they see a guy impersonating an officer? That guy is done, lol.