Interesting theory. I say theory because it hasn't been proven yet but it could well be true. We know one thing, he wasn't good at TnJ because they started a long a vicious cycle of war that transcended several lifetimes.
Are you saying that Indra didn't really want to fight but he did purely because he was manipulated by black zetsu?
That's open for interpretation. It could be understood either way. If Hagoromo made a decision, "losing a battle over leadership" doesn't have anything to do with his decision.