There is no way in HELL he gets a new bumper. That little dent if any. I didnt pull those prices out of my rear. That is estimate # 4753. I wrote everyone of them in the last 5 years. I know just a little about how things work. And not to bash your other post ,but the bedside is not much if any thicker sheet metal than the door or fender. Its all thin. A stud gun would make quick work on his dent or just pull the tail light and work it like that.
OP That estimate is written on a Mitchell estimate system. Used by 75+% of all insurance companies. Turn it in on your policy pay your deductible. You can get a claim against him for that in small claims court.
That or wait until he goes on vacation jump his fence and turn his outside water hydrant on.