Well, no. I'm not making that distinction. I'm arguing that if I showed you a picture of a woman in a state of undress, you said that you would like to have sex with her, and then when you found out that she was transgender, you lost your interest, that would be bigoted. I'm arguing that if you had sex with a woman, and you were attracted to her and enjoyed it when you thought she was cissexual, and then felt disgusted / disturbed / betrayed / deceived when you learned that she was transsexual, that's bigoted.
Right? I mean, the only difference is that in one the modification happened in utero and in the other it happened surgically. And there's way too much sturm und drang over this distinction.
That final point is truly absurd; there is obviously a tremendous difference between something created in utero and something grafted and sculpted together surgically. Perhaps if surgery consisted in suddenly altering the phenotype so that the person spontaneously and organically grew new components, you'd have a point. But since that is science fiction and will likely remain so, the distinction is very real, and many people are going to be bothered by something surgically cobbled together, seeing it legitimately as a very different kind of thing from a naturally produced body.
But putting that reality aside, there would still be a distinction even in some futuristic ideal world in which science could truly alter the body in a miraculous manner. The reason is that a person's sexuality always carries along not just their body, and not just their chosen identification, but also the way in which their desire is lodged in the two.
What I mean is perceptible with a thought experiment from the web: if one were to exchange in a kind of sex chat online with someone posing as a female, and then were to find out that the person was male, would not the reaction of some disgust or at least an immediate shift in ones response to the same words be expected? It would, because those words now mean something very different when you are made aware of the man at a keyboard fetishizing his enactment of a fictional female body, which is very different from a person who is female writing the same things. The exact same words carry a very different desire lodged in them in the two cases, and being made aware of it suddenly shifts the interpretation, not just subjectively but by making one aware of a
tone that they had not yet picked up on.
Now, the case of post-op transgenderism isn't exactly like that; first of all, the scenario above is much more like transvestism as a fetish, which is very different. Second of all, we're talking about a new body that is at least to some degree that of the presented gender (and again, let's get fictional and pretend science could make it identical). But the person's desire is still lodged somewhat differently in their body from that of a natural female, and being made aware of that fact could indeed provoke a legitimate reaction of suddenly seeing all the same things (body, gestures) in a new light that is no longer attractive at all sexually. Because the history of this person now turns out to be that of having once lived in another body, inhabiting it and feeling disjointed from it, then working to reshape that body to fit a different desire and self-relation. And that history of the person's sexuality does matter; it is a legitimately different phenomenon from someone who was born with a body and whose desires emerged from it and in concert with it. To insist otherwise is to neglect just how much our person and our relationship to ourselves is always bodily, not just in a head that is secondarily attached to this or that manifestation. Heck, even simple things like being obese versus thin cause a very different relation to your body, and a formerly-obese person can carry and comport themselves a bit differently from others; and so on with many examples, like how an extremely tall friend of mine carries a whole set of mannerisms and ways of moving his head, or standing a certain way, that have clearly emerged from towering over people, and that would most certainly leave traces even if he were one day cut short. They vary in each case, yes, but they matter.