It'd be pretty epic if Madara acted like he was believing it and then extracted Kurama from Naruto in one split second, causing him to nearly die. It'd be a nice "growing up" moment for an oblivious shonen hero to realize that Yes, there are genuinely evil people in the world.
Obito has shown a pretty good resistance to it so far, and even TnJ Naruto for awhile. Naruto was about to give up til Hinata slapped him, and thats a fact.