If it helps: I’m another trans person, approximately agree with that line, and think one expression of it is that in those indigenous cultures, trans people were held to the norms of their target gender as stringently as everyone else. I don’t know of historic cultures that do mixed-gender role mixing the way we do. AFAIK transition, in cultures that had it, was uncommon and a way for someone to move from one tightly-maintained box to another tightly-maintained box.
In other words, I don’t think “physical sex” is just one thing—for example, it seems “postmodern” and “bizarre” to me that both some pro-trans and some anti-trans people claim that taking estrogen doesn’t make a trans woman more female than she was before—but I think it’s more real and relevant than current culture admits for. (I think this came about as an enforcement mechanism for women’s rights, so on net I bet it’s a good thing.)
> And if maybe this is key to why (...) feeling sexually safe at a job has been such a royal pain these last many years
...reads like a mistake a feminist would not have made.
(Implicit assumption: “postmodernism” was coined in 1980 and “postmodern feminism” the mid-90s, and most people who talk about gender ideology date it to the last 10-20 years, so I’m assuming that’s the time period you’re referring to by “last many years”.)
Men feel a little less sexually safe at work than they did sixty years ago, and women feel vastly more sexually safe. My grandmother, and the other women her age I’ve been close with, have stories about their bosses making explicit crude comments about them, groping them at work, and the like. In the story I remember most clearly, the boss didn’t try to hide his behavior, because everyone agreed this was a normal liberty to take with your female employee. If she had complained, she would have been not only punished and likely fired, but also criticized by her coworkers for being precious about the situation.
I think separating the sexes into distinct classes (“kitchen staff are one sex and serving staff are another”) wouldn’t output a separate-but-equal situation; it would instead output a society that subjugates women overtly (again).