I think she does. The defense was a public event in the courtroom, with a complete transcript retained. Her testimony has no unique value for this phase of the case. It takes an exceptional situation to override a constitutional right, and that burden is not met in this case. I don't see a conflict between actively working in court to prevent an execution and refusing to testify in the same court on the quality of the defense, not when that testimony would aid in deciding for the death penalty.
If she elected to be on the witness list for the first trial, then she gave up the right to not be a participant. Witnesses don’t get to pick and choose to answer only the questions that will help their favored side.
IANAL but I have to disagree — I’d expect her transcribed testimony to be the basis for questions on her participation in the original defense. Her answers to those questions are new and unique information that only she can provide. Her answers would bear directly on the claim of an inadequate defense.