Seems unanimously TB.
Is that a) because the ball was over the goal line when the player's foot touched down, or b) because he did not firmly grasp the ball until the rest of his body came down?
Pretend this happened at the sideline instead of the goal line - would you have it incomplete? I wouldn't. Therefore I wouldn't say b).
In the olden days, this would either be TB or safety. So officials would fudge their rulings to avoid giving unfair safeties. The momentum rule was written specifically so we wouldn't *have* to fudge our rulings like that.
So I would say, if you have the ball at the half-yard line - or if you're not on the goal line and can't tell for sure - then go ahead and rule TB. But if you know the ball to be at the 1, then do what the rule was specifically created for.