Lawsuits challenging a censorship action or account suspension relating to censorship should be granted an exception to the otherwise binding arbitration agreement.
The purpose of this would be to deter ad hoc political censorship, and to instead encourage these companies to move towards a more procedure driven censorship system in which they simply respond to court orders and leave everything else up. So, for example, if I sued the John Doe operating this account for copyright infringement or if a law enforcement agency won a court order to get the account taken down for posting illegal pornography, that's fine, that's how things are supposed to work.
If instead the service is just arbitrarily censoring people, they have to keep strict records of their work products and produce those records in discovery. The companies would also have a hard time deflecting responsibility onto individual censors because almost anything that they could possibly do would be within the scope of their employment.
Yes, this would make what most of these companies do with their censorship teams economically impractical. That's the point.