I sometimes wonder if the condemnation of transgendered people by some feminists is linked to a fear of losing that gender dichotomy (i.e. male = oppressing class, female = oppressed class,) that supports their analysis of gender-based injustice. Dunno.
I think there's a lot in this. It's a thorny one, because there's a paradox there in some feminist thought: on the one hand, there's a desire to challenge the gender binary, as it's used to prop up oppressive social structures, but on the other hand there's a dependence on the binary as a way to describe what's there to be challenged. There's a sense in which talking about men or women as a class in order to critique the interactions between them actually reifies the differential it's trying to dismantle.
I wonder also whether there's a feeling among some feminists that trans people are in some sense 'letting the side down'. Here are these people whose bodymind challenges the gender binary in all kinds of complicated ways, who feel that body and mind in some way don't align; on the face of it they should be ideal allies in a feminist project to dismantle gender-based oppression. And yet there they go (some of them at least), these fifth columnists of the patriarchy, mutilating their bodies and taking on stereotypical gender attributes in order to conform and reify the gender norm, instead of helping to bring the whole system down!
But what gets left out of that analysis is the fact that living outside the gender binary is to be a permanent pariah. From the stares in the street, the questions of small children 'Mummy, is that a man or a woman?' to the volley of abuse in a public toilet when someone perceives you to be in the wrong one, all the way to the gang that beats you up at a bus stop just for looking 'queer'. All these things are part of daily experience for my genderqueer friends - those who've chosen to stay genderqueer, that is, rather than train themselves to 'pass' as one gender or the other.
And the thing is, while some people are willing to take that on, to see their embodied problematisation of the gender binary as a radical political project, being trans isn't a choice: it's just something you're born with. Many, many trans people don't want to be a living political statement - they just want to fit in, live unremarkable, happy fulfilled lives with loving relationships, work, family, pets etc. Can you blame someone like that for going along with the doctors at Charing Cross who say they should be more 'masculine' or more 'feminine' in order to be able to access treatment that'll help them fit in? It might not be politically ideal but to me it is eminently understandable.