I appreciate that you are on a profoundly different page than the "why do women orgasm" camp. But I think you've mostly demonstrated how tortured it is to argue that any sexual orientation is more "natural" and thus superior.

You can literally, being a man, just masturbate onto a leaf and then hand the leaf to a woman for her to pour it inside her vagina.

Right, I think it's useful to examine our assumptions, such as about the primacy of PIV sex. It can be decoupled from reproduction. But that doesn't tell us anything about the innateness of any sexual orientation. And you can go further . . .

living together appears to be the worst possible thing for them, especially as that arrives with its own set of issues which have, for thousands of years

. . . and also decouple heterosexuality from the nuclear family. In cultures where the family structure is comprised of matrilineal clans, a traditional form of marriage is walking marriage. A husband visits his wife for the night, but then returns to his clan by morning; it may even be taboo for him to be seen by anyone come morning. Marriages are easily dissolved, so sexual relationships come and go but the clan always remains intact.

Heterosexuality doesn't come with a patriarchal family structure attached. You're assuming too much.

Radical feminism has been trying to change things forever.

We don't change things by shaming or trying to change anyone's sexuality. The nuclear family is antithetical to feminism, but attraction to men is not.