He assaulted you first. He doesn't know your name. You don't know his. Even if he took the plate down, no cop would investigate a misdemeanor assault he didn't witness. Your biggest worry is if he sees your car on the street someday. I'm a judge, so I deal with these people all the time. About 5% of people don't have a place in polite society. And fully 75% of people are idiots. I'm just glad the other 70% in between don't need my "babysitting" services.