I was a little surprised by that quote since this is something you learn in skydiving class, and everyone's getting basic skydiving certification in order to start BASE. You learn on your first day that if you hug the beach ball, you will flip and fall with your back down. The easy to remember analogy is a falling leaf -- leaves always fall concave (edit I mean convex) side down; cupping the air is completely unstable.

Anyway, you're right, it's an important piece, and I'm sure the hugging the beach ball thing might become an instinct response that overrides your training and happens very quickly when it becomes obvious that you're going to collide in 0.5 seconds. But, the article also immediately follows that with 'but that doesn't explain why the best flyers are dying'.

The singular reason people are dying is because they're pushing the boundaries of proximity flying, not because beginners are accidentally stalling once they're too close.