I would argue that this line of thinking leads to an inevitable conclusion that all attraction (even with so-called cisgendered individuals) is ultimately based on illusion. That's kind of a Buddhist perspective and as such is very attractive to me (not to mention consistent with my experience). However it's not very practical. The more pragmatic perspective is closer to this one, basically that attraction has an evolution over time. Even in the case of an LTR attraction can wane for a variety of reasons, often (in the long term) having nothing to do with physical attributes.

One of the things I find so triggering about the "genital preferences" line of argumentation is the idea of locking in attraction at the earliest possible time. I have had a personal and very negative experience with somebody who tried to do this to me -- argue why I should have been attracted him based on signals I may or may not have given at an early point in time -- and when it was clear the argument was going nowhere proceeded to attempt covertly to damage my reputation. It's because so many outspoken trans people communicate a willingness to do this exact very thing that I hate them so much.