It all comes back to one simple question. How much experience does the author have in terms of cycling in traffic? Or cycling generally for that matter? In any other activity, that would be the first question asked when something like this is written. I rarely pay attention to "safety instructions" of this nature, because my own experience is usually far greater than that of the author (with a couple of rare exceptions).
Unfortunately, cycling seems to be unique in that it's the only activity in the world in which a person can get behind a keyboard and suddenly become an "expert" with no experience needed.