Right, but the primary reason you would support Manning is because you believe the government is in the wrong and that the $256k is considered coercive because the government is using it to pressure her into doing something that isn't in her best interest in regards to a fair trial.
So the goal would be to pay lawyer fees to fight the $256k of fees.
No she hasn't. That is, she was not made immune to incarceration and confiscation of money - which is what the federal state did to her. She was only immune from prosecution about what she says in her testimony. However... she had already been prosecuted for her actions and did a lot of jail time.
Plus, you don't rat people out because you've been granted personal "immunity".
So the goal would be to pay lawyer fees to fight the $256k of fees.