I couldn't agree less.
Sorry, actually, upon reflection I think he should do harder time than other rapists.
1. He's a cop, which means he used and abused a position of public trust and authority. I'm reminded of the old East German line, "When the police are beating you up, who do you call for help?"
2. He used his public authority to assault someone with unusually little power. He thought he could get away with it, because who's going to trust a prostitute's word against a cop's? What's a prostitute going to do, go public and hold a press conference?
If a wife says no, and the husband forces himself on her, is it rape? Your opinion appears to be that it is not, because of the "social contract" for sex included in the marriage.
Using his badge and the threat of arrest to get her to frellate him is rape. Your opinion is invalid, legally.