Simple empirical evidence. Have a friend jump in and saw back and forth on the steering wheel. You'll see it move, top side or bottom. I have my reservations about this brace, but my FF K-frame made huge strides in keeping everything solid.
It doesn't move as much play once the vehicle is underway. Bottom line, we need a real steering box, with a real ratio (12:1), 2.5 turns lock to lock like the rest of world. I guess ma mopar underestimated the arm muscles of american people in the 70s...