Only because you want her to be. She is attending the premiere of Undefeated. Palin could certainly tell her to shut up and stopping spread lies about Bachmann.
The stalking horse charge is absolutely a lie given the recent polls. No one with a shred of morality or ethics spreads those sorts of lies.
When she starts criticizing Romney by name then I might agree. In the interim it is still logical to conclude that Bachmann is not a serious candidate and is instead running for Mitt's VP slot.