Jeanricuser, you clearly forgot chapter 640. It's not Zetsu pulling this shit (specially considering his Zetsu part doesn't even cover the head, much less the brain to pull tricks like these), it's Obito himself (or rather, his subconscious) doing it.
And you clearly missed two painfully obvious things:
- The Team Minato isn't half them, half Zetsu because not only it is on the wrong side, the panel progression clearly demonstrates that they were shifting from Obito's current look to Team Minato, reinforcing the attempt of the subconscious to convince the conscious.
- We already saw organ rejection from Hashirama's cells with Danzou and they immediately turned into a tree. Did you see any trees hanging around Obito's body, by any chance?