The break-up hammer seems like the wrong tool for the job.
I wish people would discuss an enforced API. If Facebook were forced to federate, we wouldn't have to end it - it could be just another option in a plethora of social networks. If the data (and accounts) dispersed, we wouldn't see another Cambridge Analytica scandal, because that kind of abuse relies on repeatedly accessing massive amounts of data.
Having distributed networks would also make the kinds of lies Facebook tell about their ability to advertise much more difficult, because multiple admins would be able to verify what kind of advertising reach is possible.