I think that white zetsu is not a proper/weak host for the edo tensei. He is just a clone.
One long shot evidence is that if you look closely to Oro, you can see that he is still not in good form. He still looks so jelly and unsolid(if that is a word).
Oh and one more thing, now i know why white zetsu, was so cool in the kage summit. White has first hokages personality while black zetsu had madara's personality.