Well they are supposed to be confessions yet he does not confess the worst part of what he witnessed. IIRC he literally says "I'll tell you everything" then proceeds to leave things out. Somewhat contradictory.
I don't take them that way, Ziggler is certainly not being forthcoming with Bill. I'm not sure why you'd expect Bill to be honest about everything, I don't think that's the point of the movie at all, no less so that it doesn't make sense because he wasn't honest