Since he catches the ball with both hands, re grips, transfers to a single hand and stretches it out -- I've got a good reception. If that was the middle of the field, you might argue catch and fumble (although I think his other arm/shoulder hit the ground first).
I think the argument that didn't overturn the call here was "Was he airborne when the ball crossed the goal line?" If so, he doesn't get the goal line extended, and I can't say for sure that he got the ball INSIDE the pylon. Lack of conclusive evidence = call stands.