As for "a serious mental disorder that mainstream psychology is not allowed to treat for political reasons" - there is no psychological treatment. All which have been tried have ended disastrously. body modification is far from an ideal solution but it's the best that's available at the moment.
In the mean time, no one on FR who's gone to great lengths to criticize these so called "deviants" has yet explained what is so bad and dangerous about them. No cases have been cited where they've harmed another person, no case has been cited of a child being traumatized and permanently scared by their existence, nothing.
Truth is, ttranssexuals make people uncomfortable. Full stop. ,p> that, however, is too damned bad. LOTS of people make those around them uncomfortable. such is life. Examples could be provided but I think the cases are obvious.