I've spent quite a few years in an IP law firm. The diagrams are purely to illustrate the concepts covered in the text. They don't have to be complete. Hell, the 'representative image' doesn't even have to be relevant. Most times they're pretty close, but there's no rule that says they must.

Most everything that truly matters in a US patent application is the claim text.

The gist of 'why this is special' seems to be limited to the fact that you don't 'slide' the display itself with this invention, as you would with a sidekick. You twist the whole end of the device (the bit labeled 16 in the diagrams), and that pushes the screen part of the device 'up' through various distinct stages. Basically, you keep twisting it to reveal more and more of the keys.

I have no idea why they think it might be a good idea to do things that way. To be honest, they might not actually think it's a good idea either. Patent prosecution is an odd duck.