The first score in the superbowl?

If you recall Roethlisberger ran from about the two yard line and it was first called a TD, than reversed because his knee hit the ground before the ball broke the plane of the end zone, and the Steelers settled for a field goal. But no one mentioned the fact that another Steeler (I think one of the linemen) blatantly pulled Roethlisberger into the end zone. Isn't that illegal? Shouldn't the Steelers have been penalized for it (not that they wouldn't have kicked the FG anyway)?