People who are willing to have their sexual parts surgically removed or altered obviously are driven by something so compelling that most of us cannot even imagine it - wouldn't you agree? So if you don't understand what's driving them, it would be a good idea to exercise some self-control and refrain from creating your own theory, and opinion based on that theory. Just accept the fact that you don't understand it. That's allowed, even in the 21st century internet.
As for what you should "call" such individuals, if you should meet them (and recognize them, which you probably won't) - you should simply be what I'm sure you always strive to be - POLITE. If they've gone to all that trouble for a feminine or a masculine exterior, then it is polite to acknowledge their obvious preference, and address them accordingly.