If I were the DM, and one of the players wanted to do this, I would let them lose the fight and get robbed before explaining this particular prostitute is a retired level 20 paladin who became disillusioned with the church and wanted to pursue her new dream of being a glamorous sex worker.
Then you tell them that's what happens when you pick fights with random people on the streets. You win some, you lose some.
I'd be more inclined to handle it as "Alright. Fine. You beat and rob a hooker. You get a whopping fifteen copper pieces, and she's crying at your feet while your ally continues to stare at the lock without actually doing anything."
"Okay, good. I'll give her inspiration then."
"... What inspiration? You used it all in the last combat."
"Yeah, but I get it back when initiative gets rolled."
"... Did you see anyone roll initiative? I sure as hell didn't."
