Unless you figure that they had a great shot of not botching five more field goals in the second half.
I guess this is the crux of the argument. The Bengals didn't score any points in the second half, and really only came close to scoring once on the botched field goal. I don't think that would have happened with Palmer in. Would Palmer have managed to score 14+ points in the second half? Yeah, I think he probably could have managed that. You disagree, and of course we'll never know.
It's a shame the game couldn't have been played straight up. If the Bengals had lost with Palmer then this wouldn't be quite as tough to take.