The worst part is that a lot of them are probably perfectly sane, just narcissistic and acutely aware of the benefits of claiming to be trans (of which there are remarkably many, and are surprisingly not always offered to LGB).

I think a sizable chunk of people who are trans these days insist that a) it's not a mental illness (but they still want to have any treatment publicly funded as if it is), and b) gender dysphoria is no longer required for a person to be trans. So no, I think when they say disabled, it's usually something nebulous like neurodiversity (which can mean anything really) or an invisible illness where there are no obvious issues seen from pictures alone.