"Hm. On that note, I do owe you, but in a different way. From what I hear you're the one left to clean up all my messes." And he did, though perhaps in a different timeline.Which means he was capable, and he would and could do it again.

Except maybe this time it won't be necessary. The world doesn't have to come to the brink of ruin if Cloud and Sephiroth are both on the same page.

He doesn't refute the repetition; surely if Zack wanted it discussed he'd have discussed it. He didn't, therefore it was the way it was wanted. "... If you think it'll help you, then be my guest. We're all in this together."