Well done for this bill not being passed, it shows that at least someone knows the constitution.
With regards to having gender separated changing rooms, I feel there is at least some reason for them. I went cloths shopping a while back and the changing rooms were not separated by gender, this wouldn't be an issue if it wasn't for each stall basically having multiple holes into the adjacent stalls. I was pretty sure that the person next to me was peeping on me, after all, I don't see a reason for a person to be in a changing room, with their knees on the floor. (the knees were visible under stall wall.) Recently though, I went shopping and the store had changed the policy and implemented gender separate stalls. This time there were no holes in the walls.
I am not saying that a gender separated changing rooms will prevent anything, but I am inclined to think that doing so reduces vandalism as people who might have wanted to peek would be less inclined to do so and so wouldn't be knocking holes in the walls or every stall.