I think Andreas' point is that although there are more specs and they contain more details, they are far less ambiguous so that a careful reading allows one to achieve correct functionality without guesswork. Since he's worked on browsers for many years, I'm inclined to believe him.
Also, if you watch his browser hacking videos, you can actually see this play out live. He finds a layout problem, searches for the relevant spec, and reads through until he finds which detail was missed. He then literally copies that spec chunk into the code, then conforms the code to it. I find it fascinating to watch and I think justifies his claim.
As for Google moving the goal posts, if you read through the interview, you can see he's not interested in following bleeding edge, he's interested in the solidified parts of the spec that people actually use today.
Also, if you watch his browser hacking videos, you can actually see this play out live. He finds a layout problem, searches for the relevant spec, and reads through until he finds which detail was missed. He then literally copies that spec chunk into the code, then conforms the code to it. I find it fascinating to watch and I think justifies his claim.
As for Google moving the goal posts, if you read through the interview, you can see he's not interested in following bleeding edge, he's interested in the solidified parts of the spec that people actually use today.