I’m guessing a lot of the death is purely due to psychological and cultural pressures. There’s clearly a strong gender bias in this society simply because people get to choose their gender. As a result, genderless people have to face extreme anxiety from not fitting in or discrimination. Psychosomatic Condition are a reality, and I think that may fit here, where being gender less causes so much anxiety and stress that it causes acid effects like weakened immune systems, inattention, and so on.
As for the try itself, I get the feeling that Hinase, if they change at all, will change because they like the doctor, and not because they like the childhood friends.