This is wrong.TO PUT THIS TO REST! kabuto summoned the seven swordsmen to the same location as zabuza therefore he could have done the same to madara at muus location BUT HE DIDNT he had muu summon him so madara is going no where. plus with the rinnegan he can bring hmslf back. enuff said MADARA LIVES ON!
Muu was used to summon them because Muu is harder to detect. Nonetheless, he was detected but only detected as a single entity.
He then summoned previous Kages and Madara, after he had been detected.