That's not what the article is saying. The article is saying that the iPad is optimized for personal tasks. A personal computer is (implicitly) optimized for work-related tasks. While you certainly can use your laptop/desktop/netbook to perform the same functions as an iPad, it may not be as natural or as comfortable to do so.
I'm not sure I believe the author's analysis either. But the least we can do is represent it faithfully and not argue to straw men.
You're being way too kind to the author. He never tries to demonstrate any of the ways in which a personal computer is "optimized for work-related tasks." He just takes it as a given: "you can’t kick back and relax with a laptop." It's just bullshit, not an analysis.
I'm not sure I believe the author's analysis either. But the least we can do is represent it faithfully and not argue to straw men.