Hand-ball is hand-ball, whether or not the ball was going in anyway is irrelevant.
The fact his hand was behind the line when the ball hit it should have some relevence to it.
TV replay on the feed I was watching showed it from a camera on the goalline, presumably one of the ones used for the goal line tech. The ball was about 3/4 over and the hand was behind the ball (as you'd expect when he headed it at it) so for the centre point of the ball to be at the point offence took place the whole ball would be over the line.
