Yeah I would say that's more a misunderstanding than real attracted. Your average straight dude will be attracted to Blaire White from the waist up but reveal she has a male organ and most of them will feel repulsed. Likewise a gay guy can be attracted to Buck Angel from the waist up but the vagina's gonna be a pretty big deal breaker. We know both of them are non op but even supposing they got the surgery that'd still be a deal breaker for most people since those surgeries are not 100% replications of the real deal.

The analogy I make is of a sandwich (or pizza, etc). Let's say I love ham sandwiches, and I hate spicy foods. I see a mouth watering ham sandwich and am interested, then I bite into it and it has hot chili peppers in it.

Does wanting to eat this sandwich this mean I now like spicy foods? No, because what I saw was a ham sandwich, which I had no reasonable suspicion for it to be spicy.

Am I just gonna roll with it because "hey a ham sandwich is a ham sandwich"? Hell no, I'm gonna be grossed out by the chili peppers.

People feeling attraction to trans people doesn't mean their sexuality changed.

I do think some people can be like... let's say there's a 0-10 gay scale where 0 is straight, 5 is bi and 10 is gay. I think some men might be interested in sex w/a pre op trans woman because they're a 3 or 4 on that scale -- they're not equally attracted to both sexes like a 5 would be, but they're more open to male people than a 0. But most people would reasonably define anything from 2-9 as bisexual, since there are quite a lot of people grouped around 0 and a smaller but also substantial group of people around 10.