I always have very mixed feelings about this stuff.
On the one hand uniforms aren't always well chosen, especially if they cheap out. Although expensive is also not good so there is a conflict there.
And I wish they wouldn't present it as being a distraction for the boys.
But in a way that is actually the issue - women and girls clothing is sexualized, to the point where many girls and young women don't see it and and just think of it as "fashion". And that's not appropriate really, for them to have that unconciously thrust upon them, but it's also not great for the boys to receive the lesson that it's natural for girls to be sexualized in that way. And it's not just about them controlling their thoughts, the whole culture does it and they aren't incorrect to notice it.
As far as policing dress codes, it's fraught, and they are always going to have to generalize. I don't know about this element of separating them from boys in this case, I think some might feel it's better and more private, thought I'd want to have female teachers involved. The idea that being separated from the boys is traumatizing seems rather over the top to me.