I think the point
@Wibble was making is that people generally race to win, not to break records.
It's not an easy situation to resolve and essentially comes down to the fact that in most sports - the complaints will come in if a transwoman is successful and will do so irrespective of any rules about blood chemistry measurements. In fact the complaints will come in if any athlete improves their ranking following transition - despite the fact that peak adult rankings don't always map directly onto adolescent performance rankings.
Is that fair? In the interests of sporting competition we make unfair rules all the time - about age, weight, past performance, nationality etc. We don't however generally make distinctions based on things like foot size or height etc. More subtle differences only really get acknowledged in para-sports where there's a lot of debate around fair classification and fair placement of individuals in categories.
This is where it gets complicated and it becomes hard to resolve the social desire for inclusion against the concept of sporting fairness. The separation into men's and women's events were historically not seen as "subtle differences" - they were either like the age category immutable, or like the weight category something easy to measure and define. We knew and accepted the sporting fairness of those rules.
It's not easy to define sporting fairness, and unfortunately it's very difficult to prescribe a fair set of rules for each individual or even for each event - ask the para Olympics teams about that. Which is why seemingly arbitrary rules (like current testosterone blood level) get written and then rejected. Which sends us back to birth biological sex (and even genotype) as a starting point. It's not easy to be fair.