They actually cut it down quite a bit from what it was a grassroots law with support of politicians. And it was possible amidst the inner confusion of PSOE itself, with its transphobe "feminism" wings taking positions inside the party. There was a gap of possibility between the two discourses:
transphobe discourse representation
"we are trans-friendly as long as it's a secondary issue and you don't threaten the binary status quo" and this "trans women with penis are trying to erase us women and must not enter women toiltets"
And some sources: actually PSOE tried to cut it down a lot, but faced too much opposition mostly in the streets, and defended by the equality minister of the more leftist then-coalition party Unidas Podemos. https://www.elsaltodiario.com/ley-trans/psoe-asume-no-puede-recortar-ley-trans-aprobaci%C3%B3n-dictamen-sin-enmiendas
Also, one of the "successful" cuts was against non-binary people.
Just, this. Haven't anyone risen the point that in boxing there is segregation by weight? And in some sports by age? Also, clearly, black people in general have genetic superiority in (i think) explosive force and inferiority in swimming because of muscle fiber density.
However, wouldn't segregate athletes by "race" be called racist? Why doing so by "sex" isn't "sexist"?
Why aren't athletes segregate by testosterone levels, however way this should be measured? Or height? Or weight? Or foot length? Or age? Like, poor post-35 athletes, they can't have a fair race against 20-somethings, they have a natural disadvantage. Or, I don't know, just "marks", and let compete people with similar marks together, and let's see what people in different marks or categories have to offer. Anyone know whether if in boxing lighter fights are like faster or more agile than heavier?
All this biologicist criteria of "poor women" is bullshit. Yes, where there is a clear T gap and this gives cis women a fair competition and representation, and it has value, but it is taken to the absurd like with chess, as it's been already said.
Outside of sports, the definition of a "biological women" is also racist and eurocentrist. Like, european cis-women tend to have more hair than east-asian men. And african/black women tend to muscle up way easier than white men. Also, height difference betwen "sexes" isn't a thing in the Andes, it's just not real. And taking andinian people, they may be shorter in height and may not run as fast as a whitie, but take that race to 4000 m above sea level and let's see who can endure half a marathon and is "naturally superior".
I am really fed up by racist and patriarchal arguments trying to hide behind a science with overfunded biases.