Well, this is a transcript.
I'm not American. So I trust olivant as well as Don Cardi in what they hear. Or let me put it like this: It seems to me me that everybody heard what they want to hear.

So perhaps Brando got his paperballs in his mouth

But in the novel as well as in one of the original FCC scripts the surprising point is that Vito really doesn't want any inquiries. Why? If he initiates any inquiries, the other families, will get to know about it. As dontomassino said, perhaps he began already to suspect Barzini. He trusts his guts that as soon as he meets the other families, he'll find out who's behind it.