Again, negotiations would have to go through Disney, not Square. Any relationship with Square would be Sakurai being nice with the developers, not because they were necessary.Don't start that kind of semantics argument. It doesn't matter what kind of ownership/co-ownership Disney has in the character and franchise. Square Enix develops/produces/publishes the Kingdom Hearts series. Sora would definitely qualify as a "Square Rep" in the context of anything that would matter.
EDIT: Besides, semantics are kind of important when you are making a business transaction between two multinationals.