Obviously not a drill every coach can do.
It’s an easy way of drilling the one-arm release with bigger, heavier kids and getting them comfortable. If you’re going to pause them, holding them by the hips/waist requires arm strength. With this particular spotting method, my arm is pretty much buttressed in such a way as to eliminate the need to exhaust (or injure) my bicep.
As the high-to-low transition gets faster, the standard method of guidance spotting at the chest/hips/waist/thigh takes over.