my shitty school (NSFW) (tw touch without consent)

so Apparently one of the boys in my school are sex offenders

*ill jest give the short story im in high school and we had homecoming this is a few days later but one of the boys (who thinks hes in the friend group but we all hate him and we have told him that) was touching one of the females in our groups thigh. i fucking hate that boy and i hope he gets kicked out but with how my school is he is only gonna get a slap on the wrist.

I feel like i should talk to him or maybe beat him up after school with some of my friends and make sure that shit doesn't happen again i dont know what ill do and i need some answers.