The proof of the pudding is in the eating.
The plane in question went to the left.
The thrust reverse was assymetric.
Therefore assymetric reverse will provide directional control
HOWEVER, it might have worked out better in this situation to use more reverse on the right than the left.
Assymetric thrust in many situations can help you. YOU HAVE TO KNOW WHEN AND WHERE to use it.
Sioux City, assymetric forward thrust allowed for some steering to a disabled plane and allowed some survivors!
In a rudder hardover, if you cannot control things with the book procedures, different thrust levels could provide some degree of control.
IN a landing situation , if the conventional aerodynamic controls are not sufficient, if nosewheel steering is not sufficient, then at least consider steering with reverse thrust as a possible solution.
DO we go around the country steering the plane with assymetric thrust? NOPE. IT is something to keep in your bag of tricks, in your skill set if you will, to be used when the fecal matter hits the oscillating ventilator .