Question

Someone underwent surgery and became a woman.
Is it permitted to marry such a person to an ordinary male?
 
I saw one rabbinical court head who cites Maimonides regarding an androgynous/sex-obscured person whose sex was later exposed, and rules that it is forbidden.
Conclusion 1 from Maimonides is that sex is determined by the organ, and on that basis he seems right. And conclusion 2 is that everything follows what one was born as. In my humble opinion, that belongs to the question of clarification: what is before us? In that case, if the sex-obscured person was opened up, the matter becomes clarified; it is merely a factual revelation. In the past there was no X-ray… But now we have no question what this is — the organ says female, and the organ determines it.
 
So what do we go by: birth, or what is before us now?