Are you sure about that? Police impersonation to my knowledge do not require additional criminal actions to be illegal, and it is enough to verbal claim that you are a police officer or change the appearance of a car to look like a police car.
The only case I know where police impersonation is legal is if those involved recognize the imposter is not a real police officer, and the imposter is not trying to deceive those involved into thinking he/she is. That is some very clear criteria of both intent and results which is part of the "rarely criminal" cases where without it it is criminal.
You don't need to pull someone over and do something which is illegal for a civilian. If you just modify a car to look like a police car and driver around with it, then that is likely enough. Similar, even if you only walk around in a police uniform with a fake badge and don't do anything more, it will likely end up badly.
Context matter, which is why intent and result are part of the equation. If people are being fooled into thinking someone is a police, and someone had the intent to fool others (maybe with the intention to create false association), then that is likely fully enough to get a person charged with impersonating a police officer.
That's the equivalent of stolen valor, which is a separate issue of fabricating past accomplishments. The commentator did not claim they were a current CIA officer.
The only case I know where police impersonation is legal is if those involved recognize the imposter is not a real police officer, and the imposter is not trying to deceive those involved into thinking he/she is. That is some very clear criteria of both intent and results which is part of the "rarely criminal" cases where without it it is criminal.