So your position seems to be that in the above, the sentence in blue refers to the case in which the damage is sufficient to take both the Wild Shape and the druid to 0 HP. But that case is completely obvious and not controversial; no one would bother asking about that case, let alone answering it. So your position leads to the conclusion that not only did Crawford spend the time to explain in a tweet something that didn't need explaining, but he also chose to put that completely useless explanation in the SA Compendium. Do you really believe that?
Umm, yeah! I'll put his RAI quote below because people were not understanding the answer.
Jeremy Crawford
[MENTION=4036]Jeremy[/MENTION]ECrawford
The intent is that a druid using Wild Shape is disintegrated if the druid, not the beast form, drops to 0 hp. #DnD
3:10 PM - 17 Sep 2015
He obviously read it in it's literal form as if the DRUID hits 0 and answered it as such. He had to clarify as there are people that are interpreting it as the wild shape form and not DRUID. The Sage Advice reads DRUID and not wild shape so I don't how there can be any more misunderstanding. Even if you argue that disintegrate says as soon as a creature hits 0 hp, the wildshape is not a separate creature but a form and the DRUID still has HP. You cannot be disintegrated unless you hit 0 hp, which the creature in this case being the druid, is not at 0 hp. It's not RAW or RAI to do so! It's like saying that someone with false life casted on them will be disintegrated when their temp hp reaches 0 because it doesn't specify what kind of hp.
RAW and RAI it just doesn't do it. You cannot be turned to dust while still having HP.