Did they transition to your gender or to the oposite?
If a transsexual likes you what should you do???
Do you like them? If not tell them that you are not interested.
I should certainly like him/her, back. I'm sure I would, lest he/she do something to turn me off. I'm not going to dislike him/her, just because he's/she's a transsexual.
To quote (out of context) and old Del Shannon song:
run-run-run-run-runaway
(The "Debel" made me say that.)