its a good theory. however, if as you say the sage was half hyuuga, does that mean you believe the byakugan and its properties (control of chakra) had been activated prior to the sealing of the juubi?
if so, wouldnt it then contradict with the theory that the SO6P gained his ability of full chakra control (Rinnegan abilities, Creation of all things, separation of elemantal chakra, and general chakra mastery) after he had sealed the juubi?