What could she possibly report to the police?

To ruin the joke -- that the producer's hanging out with an under-dressed, underaged idol (who looks like she's even more underaged), and, arguably, forcing her to disrobe. It's the good ol' wounded gazelle gambit.

(You do get the idea that Anzu plays her young appearance for all it's worth; a 17-year-old who can pass for 10 must be going around getting child-price admittance to events, and trick-or-treating, and suchlike. Though that gives me the image of her trying to both get into an R-17 movie and claim she should still pay child ticket prices.)