You're confusing the terms 'transgender' and 'transvestite'. They never mentioned what the character identified as, or clearly indicated it (which is typical of bad writers shoehorning in 'clever' plot devices without taking into considerations what groups or people they are about to marginalize).
But, even if she identified as a transvestite, that is no reason to attack her in the same way, and it makes it just as bad as if it were a 'less extreme' identifier.
I'll admit, I don't exactly fall under your definition of transsexual. I think about sex quite often, and have had a decent amount of partners. There also is nothing wrong with having a fetish, so long as you don't hurt anyone and you make sure that you treat anyone involved in your fetish as a person, and not an object created just to satisfy it.
I don't mind being categorized. The part I take issue with is being involved in a movement that consistently leaves us behind. Many groups throughout history have done this, this is nothing new. It boils down to certain groups considering members of their own group 'too extreme' to gain public approval, so they cut them loose in order to gain favor with their own. Feminists were known for doing that to Lesbians way back when. And once Feminism accepted Lesbians, now they're doing the same to Transwomen. We could learn a thing or two from history.
I don't consider Trans* individuals 'lumped in' with the LGBT movement, I consider the groups banding together. The issue is that it is more difficult for Trans* individuals to find a strong voice, as many of us are still to afraid to speak up as it requires us to be seen. When HRC keeps cutting us out, we need to go storm their fucking offices and riot. Homosexuals and Trans* individuals were there TOGETHER at stonewall. This is our movement just as much as it is theirs.
But, it's a real dick move to try to gain favor for your group by attacking another minority that is also seeking rights. It's no different than an unpopular kid at school attacking a less popular kid to make themselves seem cool. If Transmen and Women finally manage to gain equal footing, or at least a consistent and equal voicing within the LGBT community, and we do the same thing that everyone did to us to transvestites, drag queens and other "extreme" gender nonconforming individuals, I swear I'm going to burn this mother fucker down.