Leftist here!
Your suggestion that if we need to cure eating disorders then we also need to cure trans people -is a false equivalency logical fallacy. To put it in plain English, while there are similarities they are not the same. Eating disorders are life threatening, for the obvious reasons. Being trans is not life threatening except to the extent that they are frequently targets of violent attacks, or prone to self harm as a result of the ridicule that they face. . In addition, while all people with eating disorders are suffering from body dysphoria as are trans people, there is evidence that many trans people are in fact, on some level. not entirely male or female and were misgendered at birth. That is not a delusion, that is a fact .
Furthermore, you’re operating on the mistaken assumption that the default goal for trans people is to facilitate their transition. That is far from the case, especially in the early stages of treatment The goal is never to hastily endorse what the patient thinks that they want at a point in time. Nor is it to mold them into what society wants them to be. The goal of any treatment is always to help the patient cope better with whatever issue they are having, and to find the appropriate solution. For the trans person that would include helping them to determine their true gender identity- and to take the necessary steps in order to be less anxious and distressed about it , At the same time we are not going to let someone starve themselves, Those people may always suffer from their dysphoria but they can learn coping mechanisms so that they won’t be self-destructive.