its all a genjutsu
Its just a theory but I think obito was under genjutsu
to put my logic as simply as possible
-madara created zetsu
-madara told obito that even if he leaves, he WILL come back
-obito is wearing zetsu almost like armor
-the enemy ninja were insistent on getting "rins" body back
-madara is still "napping"
I think that madara may have used some jutsu to send a powerful genjutsu into obito via zetsu, that's how madara knew he would come back and why the enemies wanted the body back ( it wasn't rin, the genjutsu made it seem like it to obito),
I know its crazy, but the fact that madara knew obito would Come back when obito is so insistent he wouldn't makes me suspicious...