It's one of those things, by the rules, I don't know LOL. By my eyes, he did catch it briefly and since it was in the endzone that's all it needs to be it seems. I remember the Jordy play years ago. Both feet down and then instantly knocked out by a defender standing there. But that was different, not going to the ground. he was staning firmly on 2 feet at the back of the endzone.
In the reality of the game and with the rules, when going to the ground, the receiver must survive going to the ground and maintain possession.
In the Doub's case, He caught it same as Hooper, and hit the ground and lost it. Ground seemed to cause it. With Hooper's it did not. Is that in the rules somewhere to differentiate? But neither "survived" going to the ground with possession maintained. It's not like Ford ripped the ball out as he was standing up after wrestling for it, he was rolling over from the ground and lost it almost immediately.
I have a feeling if that would have happened at lets say, the 23 yard line and it didn't end up in Ford's lap but instead on the grass, it's called an incomplete pass.
On another note, I had no idea the NFL had expanded replay to include automatic instances like that one