Rather than the people themselves... doesn't it say something about society that many people WOULD rather be women given the choice? Being allowed full emotional equilibrium and physical affection and not punished for expressing it. All without grueling expectations of "success" from imposing patriarchs. Many people WOULD choose that even with the comparative onus of being expected to birth/raise children, clean and cook.
It's also an easy choice to make if you have little expectations of career progression, or have truly exceptional credentials (just to name one angle). Don't get me wrong, I don't think this manga is wrong for not wanting to talk about the sexism our TS friends would likely experience as girls, or the kind of othering they would likely be subject to (thanks to TERFism), but this is also why I wouldn't think too hard about the poll they showed.
At the same time, of course, getting a chance to live as both sexes would certainly mean they can be a lot more flexible in terms of their own gender. This is not a psychological manga on gender (that's for Kanojo ni Naru Hi, for example), but a simple genderswap romp with a side of sexual harassment.
Also, most online groups (including queer ones, if only because of how small they tend to be by sheer principle) would tend to self-reinforce certain outlooks, whether they wanted to or not, so it could simply be that this group ends up with mostly trans (?) girls.