Ross Tucker (the guy you are quoting from): We should not care only if they’re on Olympic and World Champion podiums. The impact is likely to be much larger at the levels below that, where 99% of sport is played. That’s where a 5% drop in performance may have even more meaningful impacts, because it’s “the steep part of the curve”, where a mediocre biological male might leap into representative level, winning local events, or places on teams that compete at the next level up. Then it all comes down to the philosophy of how people value sport at participation and representative level, rather than elite levels, and it gets very messy indeed...
But we also have a subset of sports where the advantage will never disappear. This is particularly true where anthropometry – think stature/height, limb length etc – are crucial for sports performance. Lowering testosterone may reduce hemoglobin, muscle mass, strength, power and cardiovascular capacity, and it may cause fat mass to rise, but it’s not changing the skeleton, and it arguably isn’t undoing a body type and much of the size/bulk created in part by testosterone.
In some of these sports (contact sports, specifically), there is also a huge welfare issue, and so for that reason, the transgender MTF athlete poses particular concern for sports like boxing, MMA, rugby, AFL, even basketball, netball and handball.
Quite how sports sort through this issue, I don’t know...
But I respect that one can’t put a number to the problem’s size and say “XYZ is too many” in elite sport. In each case, one would be too many for a subset of athletes affected by any unfair advantage. I also think that the performance reduction may not be large enough to prevent the theoretical scenario I discussed above where some sub-elite men are able to win women’s events, and that individual variation and sporting variation will make it unfair in some instances.