Trying to come up with an unnecessary label for every nuance of human sexuality and personal expression is how we got into this million sexualities, million genders bullshit in the first place.

Agreed, however, there are distinct phenomena out there, and in some contexts, not all of them of course, it is useful to classify them. "Ant" is insufficient to the entomologist. If, however, my house was being overrun with a specific sort of ant that needed a specific approach to combat? I would then care about kinds of ants. We don't share the same objective, I don't think.

The existence of bisexuals like me who exclude trans people from our dating pool doesn't mean the bi's who are willing to date a trans person are a new sexuality.

It's not the case of willingness, or seeing the trans person for the gender identity they want to be, or seeing past that, or not caring. It's about being specifically sexually interested in a trans women because they're a trans woman, especially those that retain their penis. Specifically that category. This is not a thing that is true of all bisexual people, as you would label them. Some bisexuals are as care free as you can get: a person is a person is a person, regardless of trans or not. This is instead a highly focused desire towards trans woman, where the mixed sexual morphology of the person matters. The trans person stops being a person is a person is a person. They're a very particular kind of person, instead.

I understand you want to consider it a qualifier on bisexuality (is it one not worth mentioning?) I think it's categorically different. I never meant to imply that men into trans women are perfectly heterosexual. They are not, but I disagree that places them in the bisexual category. I understand you don't want more categories, more words, I understand the frustration with the proliferation, but my goal isn't one to give everything a label so that it can be considered uwu valid.

Those are more than sufficient to describe the bare bones of human sexuality, given that there are only two sexes and you can be attracted to only one, both, or neither.

Okay, so really bare bones. A straight man likes women and a lesbian likes women. The people who hold the same desire are not the same thing, obviously. This is the starting point of my reasoning I made elsewhere in this post.

You could reduce it that far though, even more bare bones than het/homo/bi, and it would all be perfectly precise: People who love vulvas, people who love penises, and people who love both. That, however is clearly insufficient in a general scheme, not just in some weird world I'm off living in.

I do accept sexual fluidity in these men.

I laid a brick once. Doesn't make me a mason. But if you drunkenly fool around with the same sex just once, you're bisexual for life? Or is your version of fluidity in this case that they are not bisexual, but instead are at some points heterosexual and at other points homosexual and thus considered bi/fluid?

Trans attracted men can be heterosexual if they are attracted to transmen, because transmen are female.

Transmen are female. Agreed, but I don't think it's the examination of gametes under a microscope that engenders sexual desire in people. It's the gestalt. You don't have to bite off anything about gender identity to agree that gamete examination isn't a thing.

without trying to include personal taste and kinks within those parameters

I am of the belief that these "preferences" are able to hold much more gravitas than you assume. When the "preference" becomes or is the full desire. Look at that Vice article. This person does not have a mild preference. They have a very deep-seated desire that they've gone very far out of their way to satisfy, when plenty of other, much easier avenues were available to them. That's not a qualifier. That is a thing.

On another topic, autogynephilia motivates people. We've all seen how far that has gotten along, what AGP has caused, to date, and what else it may do in the future. I'd hardly consider that a preference, a crutch, an accoutrement. It is a real thing, with a life all of its own.

Might not like it, but best treat it with the respect it deserves, and not relegate either to a mere "preference."

We are not 'doomed' when something else is brought in.

According to just het/homo/bi/ace,

Classify autogynephilics who have their entire sexuality wrapped up in that paraphilia and nothing is left for direction to others. Classify people only attracted to artistic depictions of anthopomorphic animals. (EDIT: Wouldn't it be nuts to say that a man, who's sole sexual interest in artistic depictions of male-genitalia-endowed anthropormorphic animals makes him a homosexual? Consequent to that, paraphilias must be considered to have the ability to be stand-alone, as well; not modifiers. The same way that homosexuality can stand on its own.) Etc. (EDIT #2, what about zoophilia? If you're only into horses, can you be straight if you only like opposite sex horses? And if you do have humans in your erotic targets, at what proportional trade-off between horses and humans do you make the distinction between heterosexual and zoophile? Or the much-awarded competitive archer, Erika Eiffel, who's got a thing going on for the Eiffel tower? Does the Eiffel tower even have a sex?)

Are those things weird, and out of the way? Of course they are. Are they relevant to the topic at hand? AGP is. The trans-species folks are waiting in the wings, you know. Joe Rogan's podcast had a guest on who detailed how a big tech employee wanted to crap in a litter box in the bathroom, and not use the toilet, because they're trans. Trans-species, that is. If you want to head that off, then we need a way to talk about these things. It does not have to be a perfect model. All models are wrong, and all that, it's just that some are useful.