They got around that by saying Dez was going to the ground to make the catch, so he wasn't a runner yet. IOW, at the point where the ball came loose, they say he was still trying to catch it.
But the key is that the ruling on the field was a catch. That's why it's important that Fisher is talking about "two standards" for what is a catch. In order to prove that Dez was going to the ground to make the catch, there needed to be indisputable evidence that Dez was falling down on his own (even without being tripped). No such evidence exists, and in fact we've all seen Dez have less control of his balance and still stay upright. But let's say there had been such evidence, and that it was obvious that he was going to the ground on his own. In that case, all he has to do is make a football move before he hits the ground, and it's a catch. So that means there needed to be indisputable evidence that he was not reaching for the goal line.
No evidence of that exists, either. In fact, in an interview a couple of weeks later, when Blandino was asked what advice he had for receivers in this situation, he said, "Just secure possession of the ball and don't try to do more." Of course, the "trying to do more" is Dez's lunge and reach for the goal line, which is obviously a football move, so Blandino admitted he saw Dez make a football move, after first saying that the move wasn't obvious enough. If it wasn't obvious enough to make him think Dez was trying to do more, then how else could he know Dez was trying to do more?
The field judge has his own standard for what constitutes "going to the ground to make a catch," and he did not think it was that type of play. Maybe he was basing this on the contact by the defender, or maybe he was basing it on Dez having more than sufficient time to commit an act common to the game. I lean toward the former, but in the end, it doesn't matter. The field judge obviously saw the ball come out, and marked the ball dead at that spot anyway, so he did not think Dez was going to the ground to make the catch. Why did Blandino see it differently? That's the double standard Fisher is talking about.