The difficulty for me is moving my hips laterally without my entire body moving laterally. In other words, moving my head in front of the ball. For some of us, it is not a natural move at all. Perhaps by saying he wants to keep the right shoulder quiet, he is saying how do you move the hips without laterally without also moving the shoulders laterally?
My impression from reading about the SLDR is that the position of the center of gravity on the SLDR makes the effective loft lower than the stated loft. If that's the case, the 12 degree may play like a 10.5 degree. To the OP's question, I am a low ball hitter and have benefited from using higher lofted drivers. My TM R1 is set @ 12 degrees.