Roethlisberger also stated (and so did coach Cowher) that they would have gone for the touchdown on 4rth down if the call went the other way. From the 1 inch line, their chances were excellent either way. Oh, and from the many replays I saw, I believe the tip of the ball did cross into the white line, but not over. Still counts as 6. All that is needed is for any part of the ball to cross the plane of the white line.
And there's no way Bettis would cough up the football at the goal line in such an important game, right? ;-)