anything FB does against her will undermine the PR damage control campaigns underway. They may wait for all this to "blow over" and then try to go after her once their very expensive campaigns make some impact.

It's more likely that they will collude with other big tech firm and lobby for aggressive legislation against whistleblowers to prevent something like this from ever happening.

Edit -- there are reports suggesting the whistleblower is represented by the PR firm where the current US govt press secretary held a SVP role, so her case is unofficially aligned to the current administrations agenda: https://twitter.com/JackPosobiec/status/1445438141775683584