I'm pretty sure this is incorrect. That section he is referring to in Apple's patent is just the part where Apple describes possible ways their invention might be used. In fact, if you read the intro to that section in the patent, it says "However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details." The patent claims are what's important and most of them don't hinge on whether or not the gesture area displays a visual output.