What the hell do you mean the Tuck Rule was "retroactively created" to justify helping Brady? The first application of the rule was AGAINST the Patriots earlier that year in a game against the Jets, before Brady became the starter. It was actually the game Bledsoe got injured in that led to Brady becoming the starter in the first place. Brady was just some nobody backup at the time the Tuck Rule came into being so it couldn't have been created to help him.
Patriots head coach Bill Belichick referred to this game after the subsequent Tuck Rule Game, telling ESPN, "I knew what the ruling should have been because we had dealt with that play a little bit earlier in the year on the other side of it."