We need to remember that school's first responsibility is to teach useful lesssons, and today one extremely useful lesson far too often ignored is simply that bad behavior has consequences, and consequences more often not cause, or should cause pain. I suspect we all agree that there is no excuse for a brawl at a football game, on multiple levels.
Students and spectators MUST understand that this will NEVER be acceptable, and will ONLY bring bad consequences. I suspect forfeiting a playoff round game caught the attention of a lot of people in that community who may otherwise have blown the original episode off. Was it fair to the players? I certainly don't know, but hopefully local officials who had the opportunity to see the post-brawl reaction and attitude among both players and other students, took time to observe the reaction to the original incident.
Consequences that really don't cause pain, rarely work. Consider our diddling with Iran. To be effective consequences need to cause more pain, than whatever caused the need to apply them, causes pleasure. Sometimes mules can be really stubborn, and take a lot of effort to make them change their mind and behave as is expected.