Grammar purity is a reasonable alternate explanation. My past English teachers and some of my current friends would be appalled at the use of "they/them" as a singular pronoun. I have utmost confidence my friends are not covert sexists; rather they appreciate the power of clarity in writing.
Rejects a pull request, project lead overrides his rejection, Ben goes out of his way to attempt to revert it.
Please list some reasons other than sexism why he would go to such trouble.