The best threats are open to interpretation while being perfectly clear at the same time. Effective while leaving the option open to claim innocence. He did say these are different times; implying he's not hitting anyone anymore, while pointing out that he might at the same time. Well. She got the gist.

He honestly doesn't mean to hit a girl, but he likes keeping people on their toes and he doesn't need a cross-examination of his relationship with Neil from a girl who barely knows him.

"What's your year?" He asks, casually, as if the threat had been just a story of old times. "When did you come from?"