[rocketraman]

You mistake the author's central claim. The central claim is that certain things cannot be taught or even researched if they appear to hurt the feelings of students.

Sex being binary (and the author carefully distinguishes between sex and gender) based on the size of gametes was simply one example. Other examples are discussed in the article:

  - the inability to use the terms male and female
  - fear of mentioning historical figures that are white and male to students
  - teaching the concepts of sexual conflict, kin selection, heritability
  - research about sexual selection and cultural differences
  - NIH is denying scientists access to data if their research appears to be "stigmatizing"

Your focus on one example as the central claim that invalidates the author's thesis seems like a giant evasion of the real issue.