the coach and administration gambled by tolerating his thuggery for the benefit they got from his athleticism. the gamble failed and they must pay. they are responsible for the actions of the team when they should have reasonably believed there was a chance something like this would happen. there was a history. the outraged parents can make their feelings known at the next school board election. it happened on their watch.
kinda like if a political party lies, cheats, and steals in the past, you must assume they will lie, cheat, and steal in the future.