My speculation: the repo hasnt been in active development for at least a year, all the main contributors left to found Character.AI, so Meta is open sourcing it

My speculation: the repo hasnt been in active development for at least a year, all the main contributors left to found Character.AI, so Meta is open sourcing it because it only rots sitting there and going open means goodwill, and maybe someone else picks it up and runs with it and contributes back to make it more useful.