Vox frames gender as “nonbinary,” essentially calling for women’s colleges to “broaden their mission to include all students who face discrimination because of their gender" — and that includes those who don't identify as either male or female, or who believe they fall somewhere in between.

“[Women’s colleges] have long offered women a sanctuary from some of the discrimination they face in the wider world,” writes Vox's Anna North, pushing as axiomatic the neo-Marxist precept of feminism in which women are cast as broadly oppressed by and relative to men.

Mills College, founded in 1852 as the Young Ladies’ Seminary, now accepts male students "identifying" as women. Read its policy toward transgender students via USA Today:

Mills shall not discriminate against applicants whose gender identity does not match their legally assigned sex. … Students who self-identify as female are eligible to apply for undergraduate admission. This includes students who were not assigned to the female sex at birth but live and identify as women at the time of application. It also includes students who are legally assigned to the female sex, but who identify as transgender or gender fluid.

Vox: Women's Only Colleges Should Accept 'Transgender Women'
The "explainer" blog says "transgender women" are actually women.