Never mind, I believe I have now had the curiosity beaten out of me.
I revewed about a dozen YouTube videos of walk-thrus of this model. In every one, the demonstrator entirely ignores demonstrating the TV mount in his eagerness to show off the "secret room" gimmicked behind the TV wall.
One woman bumps the edge of the TV by accident. It angles perhaps 5° before bottoming out, and she restores it.
I realized eventually that the word "PIVOT" on the floorplan does not refer to the TV, it refers to the TV wall that opens to reveal the hidden pantry. The depth of the door precludes any real storage space behind the TV, as in my model.
I am now willing to believe that Keystone made no provision to swivel the actual TV at all. Shocking.