He's got a SB ring, so to me that renders the argument null and void.
The crowd that likes to argue that he fades in big games will point out that Indy was vastly superior to Chicago in that game and nearly lost anyway.
Peyton is always going to have his critics who grasp for straws because they cannot find any other way to dispute the fact that he's one of the top 2 or 3 QBs to ever play the game, if not THE best. I've always felt like arguing a QB's merit by his win/loss record or his Super Bowl rings wasn't right. Teams win and lose games, and teams win and lose Super Bowls. More than anything else, Peyton's playoff record is indicative of the fact that he did more to individually carry his team than probably any other player in modern football. But once the playoffs rolled around and the Colts were playing the cream of the crop every week, their lack of talent was exposed.