Transition changes biology. We don't yet have the technology to fully reverse the effects of male puberty, so there can be reasonable debate about trans women who transitioned after puberty, but early transitioners have no meaningful advantage. Their bodies, in an athletic context, are female.
This is also true for many cisgender intersex women with XY chromosomes. Someone with androgen insensitivity can have XY chromosomes, yet be capable of giving birth. Drawing the line at having a Y chromosome makes no sense.
> Someone with androgen insensitivity can have XY chromosomes, yet be capable of giving birth
People with androgen insensitivity syndrom (AIS) have XY chromosomes but no uterus. So, no, they cannot give birth.
There are athletic sex differences even amongst prepubescent children, mostly caused by the testosterone surge in utero.
See https://womenssportspolicy.org/pre-puberty-male-female-child....
Quite a biased source, no? This doesn't provide evidence that these differences are biological. Boys are much more likely to exercise than girls due to social norms: https://pmc.ncbi.nlm.nih.gov/articles/PMC10478357/.
People with a diagnosis for that syndrome are specifically allowed by the new rules
> Their bodies, in an athletic context, are female.
I'm sorry, but this is not true. "Puberty blockers" do not complete suppress the effects of male genetics. They only attempt to block certain hormonal effects.
It is not possible to completely block the effects of having male genes by simple hormone modulation.
> Someone with androgen insensitivity can have XY chromosomes, yet be capable of giving birth
We do not determine eligibility for sports classes based on ability to give birth for good reason. It's not a proxy for the genetic athletic differences being addressed by these classes.
Individuals with androgen insensitivity typically cannot give birth. This an extremely rare possibility, not a typical feature of the condition.