This is so interesting! I'm the total opposite. I'm pan and realized it when I saw really masc woman/nb and was like "I don't care about the sex aspect of it".
I do feel like in takatoras case specifically there might be an ego part of it. Generally he doesn't like being seen as weak so I think having a physical reaction to the pheromones is what bothered him (I might be wrong). Regardless, it's awesome that the author has shown that it's not a choice.
Uh thats such a transphobic take dude. Its not genitalia its gender that im attracted to first and foremost and even if i do prefer certain genitalia thats a concious preference rather than sexuality. No i do not get turned on by the idea of being with a woman nor by the image of them, i am personally repulsed by it so ik im gay but u can be indifferent to women and Like guys which makes u gay too. Also if my partner decides to transition id still be there as a friend if they want me to but no i wouldnt be into them any longer as their gender identity is as valid as my sexuality is.
Theres his ego and also the "maybe if its this guy who looks like a omega and acts subimissive, if i can make it work with him i wont have to suffer living as a gay person". Also omegas are generally depicted to be into alpha pheromones, which he isnt into as hes gay. So this was probably a depiction of him suffering through compulsory heterosexuality.
Idk how well this translates into real life but i dont like the feeling of women's skin or body smell and other small things that idk how to explain but theres a huge difference in comparison to a guy's. Theres definitely biological and neurological explanation behind these things.
Anyways i personally always knew i liked guys and i like any kind of guy really fem masc tall short whatever, but the same woman wont be on my radar. I can acknowledge that they r good looking n such but theres no attraction if u get what i mean.
Ultimately i do not percieve nb people to be "nothing amalgamations who are always there" they are people with their own separate identity, evidently out of the binary so to date them is up to the individual's preference. As per that, i personally havent entertained the thought of dating someone nb, its a i'll see when i get there kind of thing for me. Same goes for trans men, im not from a place where trans people can live freely or even access medical assistance/ transitioning. The very few genderqueer friends i have, i adore them ofc but ive never felt attracted to them romantically/sexually. I def wont say someone isnt gay for being into nb, gnc folks. But it just hasnt been one of my experiences, personally.
And its not my view thats binary, its my attraction thats binary. I dont think my attraction, which i have no control over, is supposed to be some place to practice identity politics and stuff like "how woke can u get?". Its just is. You wouldn't nitpick a straight person's attraction/ preferences this way would you? I hope you understand where I'm coming from.

As a gay guy i understand why takatora wont be into an alpha even if he is his type personality/ look wise and so on. I wouldnt be into a woman even if she was cool tall handsome and masc looking in general either, the explicit example of sexuality not being a choice is so reasonable im really glad the author took their time to explain it through interactions