Malzone, looking at your post and at the ref's pool report posted above at post 28, I think you're convincing me that those who interpret the rule are putting a bit more nuance in it than what I think the best reading of the rule allows.
To state what I think is the best reading of the rule, I think it's easiest to compare two hypothetical situations. I'll use the word "stumble" to mean all the ways that a receiver can go to ground -- losing balance, tripping, diving, being pushed. And I'll use "football move" as the traditional euphemism for the act common to the game requirement.
1) Possession, body part(s) in bounds, football move. Stumble. This is a catch and there is no requirement to maintain control throughout contact with the ground.
2) Possession, body part(s) in bounds. Stumble. Football move during stumble. GTG applies, and control must be maintained throughout contact with the ground.
But I agree there seems to be some sense that at least for certain kinds of losing balance stumbles, or other stumbles that take a somewhat longer time for gravity to do its thing and get the receiver to the ground, if the receiver manages to complete a super obvious football move before hitting the ground, it may negate the GTG requirement.
It's hard to find textual support for that kind of approach, but I suppose it turns on the question of timing -- when must the "act of completing the catch" occur in relation to the components of going to the ground? If you wanted to find some support for this approach in the text, I suppose you could say that if the "act of completing a catch," as established by a football move, occurs before the receiver actually gets to ground, the receiver is no longer going to ground in the act of completing the catch. I think Dez completed a football move while going to ground, or at least had time to, although it is very close.
Edit: I guess one other way to look at it is that if a player makes a football move, then he wasn't yet going to ground. In other words, those interpreting "going to ground" give it a very specific, not intuitive meaning that maybe occurs later than we all think. It's not the beginning of the stumble or the trip, or what we might commonly say is the point when a person starts to fall. It's a bit later -- that is, when he's in position where it is an inevitable law of physics that he will hit the ground. In such cases, if you can manage to do a football move while in that position, you must not yet have been "going to ground" under this nonintuitive definition. In this case, though, when a player is horizontal when he makes his football move, it's probably hard to ever claim that he wasn't yet going to ground.