As for the theory, Madara has white zetsu spores on kabuto. If kabuto ever comes close to that clone, he will know. Not only that we all know madara waited for decades before launching the war and moving akatsuki behind the shadows. This tells me he is a patient and prudent man, you cannot easily win his trust. I doubt this is the "real clone" or if it's vital to madara plan. I don't think he would of showed it to kabuto that easely. It might be to test Kabuto loyalty. He made that clear, today allies are tomorrow enemies. He will be prudent about that!