Maybe they intend to do periodic source drops from their internal version, rather than developing in the open? That's not ideal but it's still more open than an

Maybe they intend to do periodic source drops from their internal version, rather than developing in the open? That's not ideal but it's still more open than any other heavy duty renderer. They might be worried about having to dance on eggshells to avoid accidentally revealing anything about their upcoming films, if the public could see every single commit they make.