I don't see much of a correlation between these goofy treadmill desks and user interface defaults. I like the UI example of what they do at Exec, I think it's a smart design. But the second half of the article just reminds me of Mitch Hedberg's joke about escalators.
I think the connection is that he's going to work regardless, and if the default (via a treadmill desk or standing desk) is to be healthier, he'll do that. It would take work to find a chair and sit down and be less healthy, then.