I wouldn't be proud of your nephew personally. From all I know, the other boy didn't fight back, so your nephew pretty much just pounded the kid and didn't get hit back.
It's like when Stewie shoots Brian in the foot, then when Brian is in pain he has to shoot Stewie in the foot, but Stewie doesn't want to take it.
So basicly, I wouldn't be happy for him until he got in a fight and actually took some heat then just pounding on someone that won't fight back.