The bigger question is, why were the students at the high school REQUIRED to participate in the Anti-Second Amendment protest?
Suppose this chap went out there but waved a pro-2A sign? Could they legally touch him for that?
Yes. At my granddaughter’s school, teachers planned to march the kids outside for the 17 min. protest, but decided it was too cold (teachers didn’t want to go out in the cold), so they all left classes and stood out in the hall—some protest! The kid with the detention should walk out of his detention for 17 minutes to protest organized teacher-lead protests-—now that would be a true protest.