The study was on a very high sink- way past what a pilot would see in flying any Gen Av or Commercial bird.
Simply a controlled deep sink - what the model flyers call a Harrier.
Again - the stab was pitched to match the angle the plane was taking in this "deep sink".
I would hate like hell to be in the thing.
On the models - typically there is lot of elevator control--like 45 degrees on an elevator which is over 50% of the horizontal tailplane--
This is sorta like what the study showed was a controllable setup.