Did you know at one point YOU didn't exist?What If Spiral Zetsu is Yamato and not an unconscious Yamato. Kishi stated in an interview that Yamato didn't exist at one point. Which means that he's completely lab made ( maybe ). I know that Madara created Spiral zetsu out of hashirama's cells but "SZ" could have also morph'd into a random person and turned himself in to one of Oro's hideouts. Just an Idea.
Edit - Oro just "thinks" that Yamato was a successful hashirama cell experiment, BUT all along he was already Madara's successful creation. Ya know?
Yamato isn't attacking Spiral Zetsu is, but using Yamato's power. Yamato would be inside because he was hooked up to that thing that created all the Zetsu in Madara/Obito's base.why would yamato attack the allaince? WHY would yamato even be inside?