Earlier quoted context omitted.
I think you missed the point by a couple light years. Air escaping means there's room in the case for air to be in the first place. Air molecules aren't magic, and can't occupy the same space as other objects.
So what would happen if I dropped an Iphone 5 in water?
Talking about how there's always going to be some air is completely missing the point. The point is that you can always push things a little further.