It's impossible to move people in a static and balanced position. I think the initial rotation is generated by the attacker when the nage move inside to the attacker as a response. From then, nage simply grab the head/neck,collar, whatever, to secure the rotation, unbalance attacker, and cut down
not impossible or even difficult, since most human that i know of have only two legs, not 4. something for you to think through: does a 4 legged chair more stable than 2 legged chair? hint: ask someone to stand in the most stable stand, walk around the person, then ask yourself, in which directions when you apply power would that person has the most difficult time to keep balance?