I'm aware of that, but if the cabby testifies girst, and part of that testimony is that he saw a woman dressed in a sweater and jeans come from the side of the house when he picked up the four guys on his final trip over there and that she was angry, and the cabby will be believed because he's very credible, she will have to testify truthfully about a material fact or she would face perjury charges. She would also have to explain how and when she got into the jeans and sweater. That, too, is a material issue. Further, it gives the defense an opportunity to expose the prosecutor to some extent, since he cut her a break on her bail and probation extension. They can also call the court clerk and have her testify to what documents Nifong signed off on as to Kim's bail and probation, in relation to when her story changed. This would be DEVASTATING for the prosecution. Then, the email to the PR firm would pretty much cinch her position as an opportunist trying to advantage herself through the case, including the bail and probation deal with Nifong. I would think that Nifong would be very nervous about her being called, because she was not able to keep her big mouth shut, and getting a deal on her bail and probation wasn't enough for her. Her greed really turned their deal sour for him. Kim Roberts is bad news.
When she asked how to 'spin' her story she damaged her testimony beyond redemption.