@gapstander,
The officials said that the flag was picked up because after conferring, they concluded that the ball would have been uncatchable by the intended receiver even without the contact, thus there is no penalty. The debate is whether the ball was catchable. In the officials judgement (without the benefit of watching a replay) the contact was made at about the same time as the ball was intercepted 3-5 yards in front of Gronk. Since the ball never got to the receiver, it falls under the definition of uncatchable so the contact does not get penalized.
At least, this is my understanding from everything I have read. I am a Panther fan and am happy the game was won, but after watching replays I think the officials may have made a mistake. But then, they are human and in my opinion missed a couple other calls that COULD have affected the game just as much as missing this one did. (The leg whip on Johnson that was not called would have put NE in a 2nd and 20 situation that could have stalled their earlier scoring drive. There was also a head butt from a NE player after a play ended as two players kinda jawed at each other. ) So to say NE lost because of the non-call is a bit disingenuous since they still would have needed to score on the next play from the 1 yard line and you certainly cannot assume they would have (or would not have, for that matter.)
It was an exciting game regardless of the way it ended.