The black rods are the user's will Madara said this when he created black zetsu. Naruto removed the chakra rods from Gyuki remember? Naruto was in BM... Obito said Naruto was too fast and the chains didn't wrap around him faster. Now I dunno whether the chakra rods Obito and Madara and Nagato are the same but I think they are. Someone which powerful chakra can remove them or just destroy the bodies of edo tenseis as the poeple say here I don't see a reason why they wouldn't grow back