As long as there are male and female categories, and those who were born and grew up biologically male have innumerable biological advantages on average, so you have to police the female category somehow if you are going to retain the two. That does not preclude athletes like Semenya from competing in the male, or if you will, the open category. Already the testosterone regulations enforced for trans- athletes are patently unfair to biological women where they allow not only individuals growing up biologically male to compete against biological women despite many advantages from adolescence and maturity but to have much higher testosterone levels in competition. Yet, biological women are not allowed to take testosterone to raise their own levels to those of trans-women, meaning biological males competing as women with some level of testosterone suppression.
Actually, that is false, trans-women who have been on hormone therapy for a prolonged period of time do not appear to have a NET advantage compared to cis women in events from 5km up to the marathon. Hormone therapy drastically reduces people's performance. While yes, some advantages may remain post-therapy, some disadvantages post-therapy also reduce performance by more than if the person was simply born XX. All the data we have suggests that the net result is a wash. From 5km - marathon, there is no statistical difference between the before and after gender/age-graded performances of transwomen pre and post therapy when categorised as a man and woman, respectively.
Semenya never went through prolonged hormone therapy. But she did go under hormone therapy for a short period, even then, after only a few months of hormone therapy, Semenya went from 1:54 to not even being able to break 2:02! If she took it for a long time she'd probably be a 2:06-2:10 runner. And 2:06-2:10 for a woman is pretty equivalent to a 1:54 as a man.