They've already sued her. From a motion she filed in the case:

"Given the highly charged and political context of the statements, it is clear that Powell was describing the facts on which she based the lawsuits she filed in support of President Trump," Powell's defense lawyers wrote in a court filing on Monday.

"Indeed, Plaintiffs themselves characterize the statements at issue as 'wild accusations' and 'outlandish claims.' They are repeatedly labelled 'inherently improbable' and even 'impossible.' Such characterizations of the allegedly defamatory statements further support Defendants' position that reasonable people would not accept such statements as fact but view them only as claims that await testing by the courts through the adversary process."