I would consider that kind of behavior to be a declaration that person did not value their position on the team enough, to keep it.
Maybe next year...
Just make it known up front what the penalty will be, and be done with it.
Then follow through.
Can a kid go out there and use their free speech to advocate for a car dealership, or a local restaurant before or during the game?
This IS NOT a free speech issue.
They can do it on their own time, when not affiliated with a school function.
Maybe the kneeling hasn’t gone far enough.
Maybe it needs to be both knees, begging God to forgive this now-wicked (because it’s godless) country.
The Supreme Court has ruled on the question of public schools requiring students to stand for patriotic reasons: anthem, pledge, etc. Schools may not require students to stand and may not punish them for not standing.
The school district is protecting its coaches, and itself from lawsuits.
West Virginia Board v. Brunette is the relevant case.