I liked the article; it expressed something that had been lingering on the edges of my subconscious, but that I had never brought to light - like most good articles do. What I don't see is why it had to have an anti-American bias. It doesn't help make your point, and all it does is antagonize your American readers. I am an American, I also take walks.
I think part of the point is that there is something deep-seeded in our culture that punishes idleness. That is the social anxiety he describes. I do have a little anxiety when I'm going for a walk, alone, not particularly doing or thinking anything. Will people think I'm some sort of weirdo? The observation that this worry is itself worrisome is an observation I can identify with.