I don’t entirely disagree with you but I do think there is a cultural/social difference between a cheer uniform or a sports/swimming outfit, or a gymnastics/ballet leotard even if the square inch body coverage isn’t much different.
Plus, an individual unknown-to-the-school adult dressed in a cheerleader costume on school premises is still a questionable situation and not really comparable to students of the school performing as a cheerleading team on a field/in a gym in their uniforms.
Would it be OK for this mum to turn up at the school board meeting wearing a cheerleading costume? I reckon it would still be pretty inappropriate.
What if she dressed as cheerleader to volunteer for the PTA? Or to chaperone a dance?
Or to perform on a stage for a group of teenagers who have been ‘grouped’ together on the basis of adult-world themes of sexual orientation and cross gendered presentation?
Would it be appropriate for one of the teachers to wear a cheerleader costume to teach a class?
How about the black leotard and boots outfit?
And even without all that context I desperately hope a school cheer squad is less adult-themed-provocative in both costume and movement than the professional squads are and if not, that’s a problem that needs to be looked at too!
We don’t really have an equivalent to cheerleaders in UK culture, so it’s hard to imagine what it might be like in school context - hopefully not a bad as the little-girl pageant stuff (we don’t really have that either)!