Whether their code is open source or not is almost irrelevant. Read what ESR said carefully, it's not actually about the code itself, it's about user control of their data and experience.
Appropriate, thorough APIs and policies can probably accomplish the goals of user control even better than what is most likely a maze of undocumented code that would be hard for anybody outside of Facebook to make sense of, or put to good use.
Appropriate, thorough APIs and policies can probably accomplish the goals of user control even better than what is most likely a maze of undocumented code that would be hard for anybody outside of Facebook to make sense of, or put to good use.