"An employer with two employees, both of whom are attracted to men, different only in that one is a man and the other a woman. If the employer fires the man because he is attracted to men, then the employer discriminated on the basis of sex: had the employee been a woman, she would have kept his [sic] job."
An employer with two employees, both of whom are attracted to sixteen-year-old girls, different only in that one is a man of fifty and the other a boy of sixteen. If the employer fires the man because he is a fucking pedophile, then the employer discriminated on the basis of age: had the employee been a sixteen-year-old boy, he would have kept his job.
The ADEA tracks Title VII word for word except that it replaces the categories in the latter with "age." Judge Gorsuch's alleged "logic" would put the pedophile beyond reach. Others have suggested that male and female lifeguards could legally be treated differently if they both wore only swim trunks to work. Gorsuch's "but-for" test puts all gender norms beyond reach, not just atypical sexuality. It's a really dumb opinion.
The right way to decide this case is to recognize that "sex" includes sexuality. That, of course, is a bridge too far for the self-styled "textualists," but that's because they really don't understand that words can be conceptual placeholders. Judges have no problem applying "shocks the conscience" to the conscience of the people when the test is being applied. Why, then, not so inform the word "sex"?
Some shifts in meaning must be ignored, as when "protest" switched from meaning "promise" to meaning "object." But changes in the content of words that are inherently conceptual are not violations of textualism, and a commitment to text does not require that such changes be ignored.
The Court should have held that "sex" is such a word. The Congress may not have known that our understanding of "sex" would become broader over time, but there is no reason to believe they wished any such evolution of thought to be ignored.
That's where this case should have gone. Where it went, I think Justice Alito demolished it. The case does NOT stand for the notion that sex includes sexuality. It should, but it doesn't. And that's a shame.