Your right it doesn't make sense, thats why we get bullshit like Ridoku dividing his power between his 2 sons (disciples?). I think the 10 tailed beast is legit part of the story just because of the obvious connection between Ridoku and Nagato. But, on the other hand with having Madaara being related to Ridoku seems forced.
Hopefully he is following the classic villain tactic of revealing your plan to your enemies, hoping they fall for what you stated would go down, then trick them on some, "Did you actually believe I would tell you my entire plan to you?" type shit. Like I said this is Kishimoto so I stress the word 'hopefully'...








