Carry on then discussing how lesbian PE teachers are a danger to girls.
mariamin, no one has said this. That is your inference.
Much like the general inference from the original post was that the male teacher (presumed straight) could be a danger to the girls.
Neither is actually the issue here.
As far as I can tell what is at issue is whether the OP should bring this up with the school, how teachers should supervise changing rooms regardless of children's' age, and what possible attitudes should be taken into account when working with groups of teenaged children (in this case) who are learning about their own sexuality, and trying to make sense of it.
Yes, it never goes down well when someone points out the obvious homophobia to liberal people.
Im glad you used a lowercase L. Also, this thread isn't really about homosexuality. In truth, I'm surprised someone hasn't come along to accuse everyone of perpetuating the All Men Are Rapists and Paedophiles trope.
(See, now I've gone and done exactly what I didn't want to do--got sucked in, and off topic. Bugger.)