It's a real hard line to draw peky. To someone with a hammer everything looks like a nail, and so if you ask the therapy/psychotherapy community who needs it, their answer is pretty much everyone.
On the hand there are lots of people who think that most psychotherapy is a psudo-science that can prove little in the way of results, and almost nothing in terms of a 'cure'.
The truth is, no doubt, somewhere in between that. And if she is talking about the "Trans" community writ large - with all the various types of Trans-persons, then it's definitively true that since a of of them have no need of any medicalisation, and most likely (and more frequently all the time as general ease and familiarity grows) no real need for pathologisation as a mental illness. They are not sick, they are not abnormal, they are just different. For them the DSM label is a real problem because they would like to live life w/o being labeled as sick.