Well, I don't want to wake up the argument that got going here, so I'll try to stay mostly out of that territory.
I didn't hate the story, but it was definitely sub-par. Mostly my reasons can be summed up as follows:
1. The way the scientific premise was explained, I thought he could ONLY become other men. The Y chromosome is the agent of change, so suddenly changing to a woman was outside of the realm of the possible, based on what I had heard before.
2. The ending was needlessly unclear as to what happened. I had to listen to it 3 times to guess he'd become the first lady. A high pitched voice could mean many things, such as him being turned into Michael Jackson, or being placed in a room full of helium. Why not be totally clear that a sex change had occurred.
3. To add on to #2, the reason for the scream is unclear. Many people have commented that they think it's because he doesn't want to be a woman. That wasn't how I read it at all, but since the story doesn't TELL you the reason, any answer is correct. I read it that he was screaming because he was afraid he would be strangled and quite possibly raped by the President, his new husband. But I don't think it's sexist to be horrified by an unexpected sex change. Even my own interpretation is kind of weak. The first lady could get an interview with the press if she wanted to, and could out the President's abusive ways--easy peasy. It would be unpleasant, but would be less unpleasant than being strangled to death. But even if I'd interpreted the horror as being due to the sex change alone, that's not sexist in my view. I have wondered what it would be like to be a woman, and if there were a way that it could happen in a reversible Ranma 1/2 sort of way, then that would be intriguing. But waking up and unexpectedly finding your penis gone? I can honestly say that would scare the crap out of me. Much like a woman waking up with a new appendage between her legs would be rather horrified.
4. What's the point of the contract? He's not allowed to tell anyone, and it's all done in an effort to cover up the President's felonies. Not only that, but they intend the signer to be murdered. They don't even want anyone to know this gene exists, and they insist on a paper trail? WTF?
5. Possible sexism aside, ethics aside, why the hell would the government take an infinitely useful attribute like this wild Y and just throw it away? This guy would be the perfect assassin! He has extreme longevity, he's in peak physical condition, and he can exactly mimic the appearance of another. Not only that, but these people are in extremely short supply. They've already thrown away 2 of these, by the sound of it, there may only be a handful more in the entire world. What a frivolous use of them!
6. The sex. I wasn't bothered by the awkwardness of the sex scene itself, or even the premise that he gives in so easily because of the sex. What bothered me is that she had sex with him as part of her governmental obligation, not only that, but under the supervision of a squad of other government employee witnesses. That reduces her character to nothing more than a political prostitute paid on taxpayer money. Neither she nor the squad monitoring the room really had any problem with that?