My guess would be either ignoring the problem altogether or "pulling out" of Europe employment-wise and then ignoring any ramifications of that for as long as possible.
Yeah, while twitter does have European business entities e.g. https://find-and-update.company-information.service.gov.uk/c... , I'm not sure what happens if the subsidiary goes bust or gets shut down before you've finished suing it. Probably have to take the case to Delaware.