No, he's not violating the rules, nor is he being vigilant, but my main point (in the OP) is his safety depends less on him being vigilant that does the safety of a driver who is not concerned with following rules such as safe following distances.
Which is why I personally prefer the philosophy of defensive driving, which Hurst adapted to cycling in his book.
My grandparents and parents have often espoused a "VC" driving philosophy to me while I rode in their cars with them. It went something along the lines of, "follow the rules, (be destination, speed oriented) don't change lanes unless you need to make a turn or really must pass a slowpoke, keep a good buffer between you and the next car. Do all that, and just pay attention to the road ahead." They didn't pay to much attention to other cars unless they were at an intersection or merging. They felt that since they were driving correctly they wouldn't ever cause an accident. In one sense they were right, they never caused accidents. But they've been victims in many accidents because they didn't avoid a bozo.