First of all, you're not completely correct. There are a few players known for having killer post fadeaways off their non-shooting shoulders and use them quite frequently, such as Melo, Dirk, and Z-Bo. I'm pretty sure Wiggins does, too.
But I want to ask you, are you 100% positive that the "Left" and "Right" in those tendencies stand for Left and Right turning shoulder, as opposed to Left and Right block, where they are shooting the shot? The latter definition would be more consistent with every other tendency where they have a Left vs. Right as two separate tendencies. Just checking to make sure you've tested it.