Transgender people are probably more hated than any other minority and hate-speech that would be completely unacceptable made about any other group often goes unchallenged when made about members of the transgender community. So it's not at all surprising a member of this group is having trouble finding her legal defence. And that's a problem.
I'm not sure Bradley Manning would have had a considerably bigger chance of getting pro bono defense than Chelsea Manning does now. Her transition may be a factor, but I'd wager it's not the biggest one by far -- even Snowden is widely regarded as a traitor in the US and he was considerably more nuanced about what confidential information he handed to the press.
>Transgender people are probably more hated than any other minority
They are the second most hated. The most hated is the one hate groups compare all other minorities to when attacking them. The catch is that the most hated group has far better ability to pass than transgender individuals, meaning that a 'which group is worse off' classification is harder to determine.