Neville, i should be clearer; that’s exactly how poskim discuss transgender people. If someone is suicidal, we don’t tell them that they cannot do those issurim; that particular mental illness induces suicide very often; it’s not a quality of life issue. This is how rabbonim have been paskening since these shailos started; it’s all in that sefer.
It’s very easy for me to look at someone delusional and tell them what’s real and how messed up they are and how they can just work on it and they’ll be fine, etc… But it’s not going to stop them. The delusions are extremely powerful.
Obviously every alternative should be sought first and the person shouldn’t be made to feel as though it’s ok to do what he’s doing, but stopping someone from committing suicide is considered pikuach nefesh.
But there are limits; even under pain of suicide a man cannot marry another man, etc.. No matter what he “identifies” as.