oh I saw the replays last night, too. and that ball sure looks like it broke the plane. even if by a half inch - that's all it takes.
it is incumbent upon the challenge to prove tha call wrong, not to prove that it might have been wrong. the ref doesn't have to defent his call. the challenger has to show that it was wrong.
What I want to see is the low-angle shot of that same play, the one aligned with the plane of the end-zone. I know it exists, at least in video, but I have not been able to find it on the net anywhere. Unless I am totally blind, the ball broke the plane of the end-zone when it was approximately 2-3 feet off the ground, then Roethlisberger was hit and pushed back by the defender. The low-angle shot (I believe) will be the hard proof of the TD.