It says many months or years. It does not say they will retain muscle mass indefinitely… I’m sure it varies per person. The easy fix for this is to just test and require trans people to wait like a year or two before competing… that’s what the Olympics used to do and it worked fine… also there are massive differences in muscle mass among female athletes. Also among male athletes. Each category has an extremely broad range. There is also a wide differences in other measures like how quickly someone puts on muscle, etc.
I mean I don’t like really care about this issue at all. But like I dislike the idea of categorically banning a group of people from sports. Especially when it’s like kids sports… kids who were assigned male at birth have zero advantage over kids assigned female at birth until puberty. And when they hit puberty they can start hormone blockers. If society would just create structures to support trans kids more, then the issue wouldn’t exist at all… people who are trans would just transition young and there would be no difference between them and cis people of their gender.
That’s why supporting trans kids is so important. My friend’s daughter is trans and she is delightful and sweet and kind. She should be given the opportunity to play sports with girls her age just like any other kid… she has literally zero advantage in anything. Plus sports are supposed to be fun and uplifting… no one should be banned from that…