It's a bluff. If they actually sue him, that means discovery and depositions. All he's got to do is get a couple dudes to say she sucked their dick for favors and he wins. Even if the jury doesn't believe him and she wins, all of the shit produced during the trial becomes a public record. Her attorneys have got to be advising her that putting private emails on statements about what a trashy slut she is in court records is a bad idea.