Whether you think she is developing "insufficient levels of testosterone to develop into a male" is completely beside the point; she is not intending to become male; despite her so-called deficiency she produces way more testosterone than her female competitors - and it is that which gives her such an advantage, that she wishes to preserve, and the IAAF seeks to address.
Excellent, now we are getting somewhere.
It is not completely "beside the point" because how and why she produces testosterone is extremely relevant and the reason she will prevail. I have no proof that this is what her attorneys will or have argued, but you cannot force someone to depress their testosterone levels especially when it would/could be detrimental to their health and well being. Testimony from any licensed endocrinologist could explain the likely negative effects that kind of hormone therapy would inflict upon a XX DSD subject.
The reason I went into such detail on the XX/XY issue, is because so many were using that as the justification to exclude her from running with women. Stating that she is "most likely XY" without any actual knowledge of such, is the type of misinformation that has fueled this discrimination for over a decade. The article in question made a flawed assumption that she is XY and then used that as justification to come to their conclusions. It's called GIGO.
I suspect that the same people that say the determining factor should be XX or XY, will yet again change their stance when they find out the true facts and find some other criteria for exclusion.
And finally, just for $hits and grins, here's my unscientific, factually questionable, probably politically incorrect 2 cents.
Does testosterone help her in the 1500 and up? Not even a little bit. Semenya's best 1500 ranks #326 all-time and the science certainly does not support what the IAAF is attempting to do. Does testosterone help her in the 800? Probably, but not nearly as much as people believe. If it was that much of a factor she would be an even better 400 runner. She sucks at that too. Was it fair that Tom Dempsey was born without toes on one foot and used that to his advantage as a kicker in the NFL? I know some people say that it's not the same, but I say it is. Yes, it sucks for the other women who feel that they can not be competitive, but sometimes life just isn't fair.