We didn’t have a pool in any case, but I definitely would not have taken swim under those circumstances. Unisex bathrooms/dressing rooms in my vision would be for one person at a time! I never wanted to see my classmates nude, and I didn’t want them to see me nude, either. I will make such decisions independent of school officials, for sure.
That female teacher was abusive! She had no reason at all to enter when children were undressed.