To those commenting that abuse as a reason for gender disappointment must be rare, given that close to a third of British women will experience some form of domestic abuse during their lifetimes, it's probably common enough it shouldn't be discounted as a very real possibility. And also one that I don't think people should be forced to disclose in order to justify their reactions.
With regards to commenting that people who are afraid or disappointed when they discover the sex of their baby due to past abuse ought to have therapy and sort themselves out before having children, that's fine in principle but ignores two things. Firstly, that not all children are planned or arrive at ideal times. Secondly, therapy is not a magical pill that removes all negative effects. People who have survived abuse will very likely struggle, to some degree, for the rest of their lives, and the things that will trigger those feelings aren't always predictable. For many, therapy will be the tool that allows them to process their feelings of fear or disappointment and ultimately overcome them, not the tool that means they don't experience them at all.
Finally, while I agree that having a penis or a vagina is no indicator of future interests or behaviour, gender roles are prevalent in our society, regardless of our personal attitudes towards them. My daughter is a baby. I can't predict whether she will grow up to enjoy sparkly princesses, football, science or sewing, but I can predict the kind of social pressures she will be more likely to experience, and it will be my job to help teach her how to respond to them in a way consistent with her personality and the ethical values I hopefully manage to impart. A person doesn't need to have experienced abuse in order to recognise that they may feel more qualified to deal with raising a boy or a girl in the face of those predictable social constructs. These are pressures we've all experienced so imagining how we'll help our children face them and how their gender will impact on that isn't a weird thing to do. Having an emotional reaction to that isn't necessarily avoidable.
The real issue is how you deal with this. I COMPLETELY agree that there are people out there who want a specific gender for really stereotypical, gross reasons, and that some of those same people let their future kids KNOW this and that has lasting, and awful results on those kids. That's awful.
Other people just like to process in public. I'm not a sharer. If I had experienced gender disappointment, I would have held close to my chest and kept it secret and tried to work it out on my own. Others are different.
In sum, the picture the OP has painted is pretty awful, and I would probably judge that specific woman, based on the specific circumstances outlined, if they are accurate. But to extend that to a judgement of all people who have ever experienced gender disappointment is unjust. Most either have strong, painful reasons, or just want to be able to vocalise some of their fears and talk it through.