It is unquestionably the case...
Why? How do you know so clearly that absolutely no indication of sexual organ would have been visible at that point, given that the foetus was 10-12 weeks and those organs have finished forming not long after that? Why is it so unquestionably the case? And why is someone going through a miscarriage in the first trimester advised to have a pair of scissors on hand, if there is no possibility of any kind of umbilical cord? I think you have some answering to do.
statement of gone's is particularly bizarre
You're dodging that issue with a remarkable lack of agility. We are not talking about the law but the justification for the moral principles informing the law. It's not enough to say that a woman's rights can disappear at viability because the law says they can, providing there's nothing wrong with her baby. If the woman's rights rest on being able to do what she wants with her own body, surely she should be able to do as she thinks best for as long as the baby is within her, or even dependent on her? Most pro-choicers draw the line at aborting a fully formed baby that could live outside the womb, but there is actually no reason why this should morally be the case, by your standards, because the argument didn't rest on whether the baby could live outside the womb, but upon the fact that it was depending on the woman's body to survive - something that continues until birth if not beyond. As far as I can see (unless you are able to engage with this question and put some other view forward), the woman's right to bodily autonomy is only a strong enough argument while the baby doesn't look like a baby. Which makes it more about emotions and what we feel comfortable doing, rather than anything particularly to do with bodily autonomy.
I can accept that because, as I've said, this is a balancing act. And there is a kind of parallel balancing act playing out among pro-lifers on the other side, because their stance falters when the life of the mother is in grave danger, or when her pregnancy is the product of a rape. Life is murky and complex; it would be naive to think there is any rule of thumb that, if applied in all circumstances, would be palatable to either camp. As is illustrated on the pro-choice front by your unease (I hope) at the idea that while it would be morally flawless to administer a lethal injection to a full-term baby with Down's Syndrome five minutes before birth, the same act would be a murderous tragedy if administered five minutes later. Or if you'd like another example of where there law just doesn't fit any decent ethical code that I've ever heard of, that woman who was sentenced to prison for going through her own late-term abortion was condemned as an absolute scumbag, but would have been sympathised with and condoned for having the same procedure if her baby had Down's Syndrome - note I didn't say 'no brain', but Down's Syndrome.