One hand = possession. How many times have you seen a player score while reaching out with the ball in only one hand? I've seen it, oh, a good 200 times (conservative estimate). This was a TD, but when it happened, live, it was bang-bang, and the ruling on the field was a fumble. I can see why they made that call, and I can see why the replay didn't overturn it. I just disagree with it.
There's a stop-frame shot .gif floating around the interwebz from the TV feed showing the ball crossing the plane - albeit at an angle - in possession of the PSU player. That's a TD, period, end of story.