OK, here's what I found that speaks to the quote that you left from Leonard Sax. It's from Intersex Human Rights Australia:

"IHRA does not support the analysis by Sax, largely because we attribute a different meaning to the word intersex, based on lived experience. Many intersex people who fall outside Sax’s narrow two definitions face stigmatisation and suffer human rights violations in the same way as intersex people who fall within the definitions, because their physical development does not conform to medical or social norms for female or male bodies. Many such individuals, including people with XXY, hypospadias and MRKH, have helped found and help lead the intersex human right movement."

I always side with the lived experience of the people in question. And, I always put quotation marks and attribution around words that aren't my own. 😉