Yes, in appearance Hogan did have a flatter swing than most but only because of his height, build and posture. Nearly all of the great ball strikers in history have had their left arm matching their shoulder plane at the top of the backswing regardless of stature.
It Brandle Chamblee is the one who made that comment, I think you can pretty much disregard it entirely. I disagree with almost everything he says. Just my opinion :)