User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-25732759-20141120220802/@comment-24502975-20141120235858

It's Cao Cao, I think he knows what he's talking about, especially since he was(still is) a close ally of Indra.

...Or, you could just go the "Ishibumi wouldn't say that if it was false" route.