Speech reasonably interpreted as bearing the school’s imprimatur falls outside the scope of this opinion so these comments would need to be made personally and

Speech reasonably interpreted as bearing the school’s imprimatur falls outside the scope of this opinion so these comments would need to be made personally and not "as the school team". The opinion still allows students consent to additional restrictions on their speech. Requiring such consent to attend regular school isn't allowed because students are required to attend school. But requiring such consent to participate in extracurricular activities like sports teams would still be allowed. So in your example the school would simply need to require consent from students to have their speech restricted before they can participate in extracurricular programs like the football team.