I learned to shoot in the Marines and I've been shooting the same way every since. The off hand being the feet, hips, and shoulders all being in line with the tgt with the spine stright as it can get with your forward elbow and upper flat along the rib cage. With a long heavy rifle that's made for 1000yrd comps I can see leaning back to off set the weight of the rifle. Or some one with a slight build would have some problems counter balancing a bull barrel bolt gun. But this guy was using a palma style rifle and acting like it weighed 20 lbs. I use a M1A NM no lite stick and can use a square upright off hand stance for about 30 min max (sit down rest between shots). I can hold my own with the rest of the pack and edge out on a good day. I don't see too many other shooters doing this and I think that the whole shift hips thing is a situational topic, and just dosen't work for me. So being the only stupid question is the one not asked I thought I'd send it to the board and see who would bite.
Start brain, then engage mouth!!