Aziraphale doubted very much if these ideas were 'merely' the musings of an old man. He was clearly far cleverer than he was giving himself credit for, at least out loud. After all, he made a very good point: there was crucial information missing and a number of logical gaps in the story as it had been presented thus far.

The only reason Aziraphale could see for keeping that information out of the public eye was if it would make them more difficult to contain - as Owen had said, herding cats - but he didn't mention this aloud because it was too cynical for him to be even thinking. Probably a result of too much contact with Bad Sorts. Instead he asked, "I wonder if any more information will be available once we get to the City?"