If they are going to do it and not back out then they should just put it into a irrevocable clause in their terms of service and promise to delete all user data

If they are going to do it and not back out then they should just put it into a irrevocable clause in their terms of service and promise to delete all user data and send all advertising revenue generated from the user to the user on request if they fail to fulfill their legally binding promise. If they are committed to it then the clause has no effect. If they do back out and the customer feels betrayed and they feel like Meta lied to them to get them to signup then they can demand Meta to remove their presence and pay the amount Meta made off of them by tricking them. Simple and clean solution with aligned incentives. If Meta does not intend to back out then they have nothing to lose.