Yep. It's not like they were kicking him out of school. Often there are certain rules that people who have participate in extracurricular activities have to abide by --rules that aren't necessarily applied to the rest of the student body.
When I was in high school, there was no smoking age. Students could smoke. In fact, there was a sanctioned "student smoking area" adjacent to the rear entrance. Athletes and cheerleaders were prohibited from smoking (among many other rules) and if caught could be kicked off the team. To participate in extracurricular activities, they had to abide by a standard that wasn't applied to the rest of the students. That's just the way it was.
Some rules are about looking neat and clean. Too bad people object to putting on a good appearance. :-)