I had thought most of the squatting talk on this was about more weightlifting type squatting and not just being able to rest in a squatting position.

Unless a deep squat = squatting restfully. Which is hard to argue that it's not due to lack of flexibility.

Great explanation, but what an awful awful site design. The last thing I want an image to when I move my mouse over it is twitch and suddenly display less information.

Except that provides absolutely no evidence to support the hypothesis. People have variations in wrists and forearms too, it does not follow that some people are "morphologically incapable" of using a mouse for example.