I say the following knowing the entire episode is messed up.
If your son hadn't responded to the bullshit, multiple times apparently, none of this would have happened.
You have to know that crowd behavior nowadays is terrible. People just love being assholes. So, being a Hawk shirt wearing attendee in their stadium is probably going to attract unwanted attention.
Best to let the shitheads have their "idiot fun" and Be The Adult...and let it go unless it involves anything physical or with children.