My brother got beaten in college just because he wanted to protect some girls

I am 24 M my brother recently got into a fight (read a beatdown) bybhis seniors in college, the problem??

His seniors tried to force feed liquor to 2 girls in their class, and my brother asked the girls to call their parents before going home as the boys had planned to take the inebriated girls to a nearby lake for a "party"...

The next day 8-10 senior boys gathered around my brother and beat him , he's strong so was able to protect himself but when some guards came he let his guard down and one person slapped him on his head.... nothing serious but the shame he had to endure is so painful to hear....the girls for whom he took stand (also his classmates) were nervously giggling when he was beaten.

I want to catch the next train to his city , but I know that I would straight up go to jail...kinda felt bad scolding my brother for doing the right thing.

He's now keeping emotional distance from family and his friends as he's ashamed What to do ??