Late to this conversation and perhaps everyone is already well past this but in my opinion the Referee made the wrong call on the review.
No where else on the field would that have been ruled a catch. The receiver did "go to the ground" in the process of catching the ball (and this note indicates it is regardless of whether contact was made or not). In that case, possession or "determination of a catch" cannot be made without the application of the requirement that the receiver "must maintain control of the ball throughout the process of contacting the ground". And, the note goes on to state "whether in the field of play or the end zone".
The referee used the "complete a move normal to the game", but ignored fact that if they go to the ground, that note does not lose it's effect and must also be applied.
Does the NFL publish a "right, wrong, etc.." on calls each week? If they do I'm positive this will be noted as the wrong call.