This play was a sack for safety which resulted in the offense keeping the ball and running another play from the goal line.

http://cust17.preview.myfootballnow.com/gamecenter/view/1731#323052

Forward progress had him out of the end zone in this case.

Forward progress? he never moved forward on the play. This is plain and simply a safety without question.

When he turns and goes back into the end zone is when the defender made contact with him which was out of the end zone. It's not rendering clearly (it looks like he's running away, I admit that, but what actually happened is he got hit forcing him back into the end zone).