McKinnon, who transitioned in her late-20s, says that results in "pretty radical physiological changes", with muscle mass, strength and speed all reduced. It also, claims McKinnon, "compounds ageing".
In essence, she maintains, it puts them on a similar level to women of the same size, and there are set limits to the amount of testosterone transgender athletes can have in their bodies before they compete. That is an issue currently being debated in women's athletics.
"compounding ageing" and "radical physiological changes" are irrelevant - you still can't change sex. By this logic you might as well have competitions for 'women and older or less fit men' or 'women and male athletes with a disability'.
This bit doesn't make sense either:
Critics say it is unfair to have a trans woman competing in female sport with a biologically male body, though McKinnon says that view goes against point four of the International Olympic Committee charter, which says: "The practice of sport is a human right."
Plenty of people can't take part in the Olympics, and plenty of people can't take part in some sports because of physical (or financial), limitiations, but nobody is stopping McKinnon from practicing or taking part in sport - the only issue is correct classification.