I agree with your criticism of those who stigmatize mental illness. But I don't think that we need a psychiatrist to tell us that people who are 12 times more likely to commit suicide than the general population are not in severe emotional and mental distress.
1. That suicide rate could be higher because of the stigmas created.
2. It could also be because lots of mentally ill (in other ways) people self-identify as transgender for various reasons (to get attention, to belong, to have rights, and possibly others) and the suicide rate has more to do with those people’s state of mind/mental condition than their “transgender” status.
3. Some transgender people have gender-identity issues because of gender imposed upon them by crazy parents, that can drive a person to suicide.
So I would say it depends.