Depending on who you are and how it happened, if you get attacked and fight back it can be self-defense in the school's eyes, meaning he can beat his a_ and still only get 5 days suspension.
My school had a zero tolerance policy meaning if you fought back you were both getting expelled. If you were lucky and had a good record theymight consider just suspending you, but that usually didn't happen.
If your school has a zero tolerance policy then I say smart move. If not then I'm not sure how I'd feel about it. I doubt he'll get any money fromit and if he does it'll probably only his family having to pay medical bills if there were any. Like 5thGearidah said though, I think he was just tryna save face.