" I’m also not sure what will be the case when gender reassignment starts early so that normal male musculature is arrested."
You only need to check the records for Little Athletics to see that boys are faster and stronger than girls from a very young age, under 6s is the youngest age for which they have records(in some states). Boys run faster, jump further/higher and throw things further from that age onwards, the gaps do grow as boys mature but it's never going to be an even playing field for women having men competing against them in any sport where physicality comes into it
