My view is that testosterone is a reasonable thing to discriminate on because:
1. It is causally connected to primary and secondary sex characteristics
2. It has a large impact on performance in many sports
3. It's easy to explain to most people and somewhat matches people's intuitions around fairness
But, yes, it is true that there are cis women with high T levels and it is somewhat unfair and arbitrary to include them when not excluding other random advantages that people have. I'm just not sure if I have a better solution
It's dumb because there are two types of hyper/hypo-gonadism. "Primary" hypergonadism is where you have way more of the hormone in your blood stream. You're advocating testing for only "primary hypergonadism" in women.
Secondary hypergonadism is where someone has a normal concentration of the hormone in their blood, but they have an unusual abundance of hormone receptors.
The effects are the same, but currently we can only measure secondary hypergonadism during an autopsy/dissection.
1. It is causally connected to primary and secondary sex characteristics
2. It has a large impact on performance in many sports
3. It's easy to explain to most people and somewhat matches people's intuitions around fairness
But, yes, it is true that there are cis women with high T levels and it is somewhat unfair and arbitrary to include them when not excluding other random advantages that people have. I'm just not sure if I have a better solution