I understand what you're saying goose, it's probably a bigger thing than just changing the rules in one instance or for one type of sport like that.
I knew growing up in the 70s 80s that I could wear either boys or girls clothes and indeed the majority were the actual same items. I'm sure there were social divisions and things I classes as for boys but I certainly remember knowing I could do either.
I have a vivid memory of being a child at school and playing in the home corner. A little boy used to play with us too. I remember vaguely that he was teased for this. One day he was crying in the playground after being picked on and told he couldn't play in the home corner.
He vehemently, out loud through his tears, wished he was a girl.
For me though I remember everything was a choice. I felt I had a freedom he didn't.
(I told him not to be so silly as then I couldn't kiss him and gave him a peck on the cheek which cheered him up.)
I think this is deeper than just an outfit for this child but still sex matters in sport and I feel they've been misled and as oldcrone says, are a victim too.