It doesn't really fit in his pocket; quite a bit is sticking out. Sitting down might be tough and dangerous with that chunk in your pocket. Putting something that large with a glass screen in a pocket could go crunch when attempting to sit.
Only something about the size of an iPod Touch is really practical for putting in a pocket.
He also likely searched his closet for pants with a big enough pocket and even then this isn't practical. It likely isn't even comfortable walking with this in your pocket and forget sitting down.
Pocketable to me means I can slip it into the pocket of a button shirt, so I can sit down comfortably and worry free. Anything beyond this size isn't really pocketable and is just transportable.
That said, I do think Apple could use a model in the 5-7" range. They really could use something to work for a server in a restaurant. To do that they need to hold it across in one hand, so they have a solid grip, not balance it like they must do with an iPad.