"Eric Vilain, the director of the Institute For Society And Genetics at UCLA, worked with the Association of Boxing Commissions when they wrote their policy on transgender athletes. He stated in Time magazine that "Male to female transsexuals have significantly less muscle strength and bone density, and higher fat mass, than males" and said that, to be licensed, transgender female fighters must undergo complete "surgical anatomical changes ..., including external genitalia and gonadectomy" and subsequently a minimum of two years of hormone replacement therapy, administered by a board certified specialist. In general concurrence with peer-reviewed scientific literature, he states this to be "the current understanding of the minimum amount of time necessary to obviate male hormone gender related advantages in sports competition". Vilain reviewed Fox's medical records and said she has "clearly fulfilled all conditions." When asked if Fox could, nonetheless, be stronger than her competitors, Vilain replied that it was possible, but noted that "sports is made up of competitors who, by definition, have advantages for all kinds of genetics reasons"."
Seems they have accounted for the differences in the rules by obliging hormone therapy.