Wrong class, that's what they have lesson plans for. You know math is taught in math class, English is taught in English class, history is taught in history class, and cheer leading is taught at cheer leading is coached after school. Simple!
No class does nothing but its subject every time, all the time. Everyone knows that much time in school is spent on socializing and other ephemera. When I was in high school, cheerleaders would come into classes on Fridays and do cheers. On Valentine’s Day, there would be singing telegrams and deliveries of flowers or balloons.
So unless she did this all the time, or the specific activity was beyond the bound of taste (cf. my original post), then I don’t see the problem.