Hmm, Mr. Burn didn't seem very informed in particular about the history of sex testing in sport.
He said 'My suspicion is Caster is 46XX, so could not be excluded on chromosomal testing, but nevertheless has an exceptionally high level of male hormone for some reason biologically so has developed a male physique'. He went on to say that if Caster does not have a medical condition then should not be subject to medical treatment, and compared Caster to a very tall boy being subject to growth restriction.
This is all very disingenuous, as he did not give any explanation in his capacity of professor of genetics as to what 'some reason' for male testosterone levels might be (although again he hinted at it previously, when he pronounced it 'testes-terone')
He had also earlier explained about the SRY gene, and the chromosomal testing he discussed is not even on the table.
As noted here:
www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(05)67843-9.pdf
"The International Olympic Committee first, however, replaced X chromosome testing with DNA-based methods to detect Y chromosomal material, principally the SRY sex determining locus, beginning at the 1992 Winter Games in Albertville, France"
So there is no question of chromosome testing!
It continues that the testing was scrapped because it was expensive and did not seem to be useful in that 8 of 3387 athletes tested SRY+, 7 had CAIS or PAIS, and 1 had 5ARD (and previously subject to removal of testes), but all 8 were eventually cleared to compete.
AIR from another study there are more athletes than this who have 5ARD and gonadectomy has been performed on a number - it seems to have been the key to ensure participation as a female. This obviously presents a moral dilemma in that my understanding is that 5ARD generally results in male gender identity after puberty, something that castration would tend to eliminate. So you have/had impoverished athletes being castrated in order to compete in female sport.
The default thinking in the past seems to have been 'it is unfair to exclude athletes unless absolutely necessary', and this has resulted in people who perhaps in the 5ARD + gonadectomy cases may have otherwise fathered children being allowed to compete in female sport.
This presumably was at least partly on the basis that these athletes were not exactly world-beaters.
Semenya has changed that presumption by winning everything, so now rather than 'let these people with biological differences compete, what's the harm?', we are saying 'is it fair that women should lose to athletes with testes?'.