What a twit, fancy insulting all the experienced helo pilots on here with bogus physics.
On a related note, I remember reading somewhere (Wagtendonk I think) that the roll during retreating blade stall doesn't necessarily always go toward the retreating side. There's no definite reason it should as far as I can reason. Yes, there is disymmetry of lift due to advancing/retreating blades, but then gyroscopic precession takes that and turns it into a flap back.
I know gyroscopic precession isn't 'perfectly' 90 degrees so perhaps that is where the roll component is induced? I suspect there is more to it than that though. If Wagtendonk is correct then perhaps the shape of the helicopter's fuselage may have an effect on which direction it rolls?