People’s bodies are still organized around the production of either sperm or ova, even if they’re unable to reproduce due to a developmental issue. You can call that a third category if it’s useful to you, but that doesn’t form a third sex as understood by biologists.

Intersex is a confusing term, and doesn’t dispute the binary. People are still male or female, with https://en.wikipedia.org/wiki/Disorders_of_sex_development