Is anyone seriously debating that sex isn't binary?
Gender being different from sex is not a new concept, from the 2001 IOM report (predating the "gender wars"):
The committee defines sex as the classification of living things, generally as male or female according to their reproductive organs and functions assigned by the chromosomal complement, and gender as a person’s self-representation as male or female, or how that person is responded to by social institutions on the basis of the individual’s gender presen- tation. Gender is shaped by environment and experience.
Not much has changed regarding sex from 2001, we've expanded the definition of gender which is clearly much more complicated.