I’m pretty sure that if in collegiate competition women in the United States were forced to wear bikini briefs, they would have legitimate grounds to claim a Title IX sex discrimination violation. I can’t imagine any legitimate reason why that sort of apparel is necessary for the sport, and if women are being held to a different standard than men than it’s not permissible legally.
That a different woman in a different sport was gigged for the exact opposite reason is really ironic, especially when she claims that her shorter shorts are necessary for her sport.
This is blatant sexism and in the case of the volleyball players, blatant sexual exploitation.