Haven't read the whole thread yet, and haven't seen the article in question, but it's unfortunate, but there are a lot of reasons why that picture could have been like that, even if he did know (and that is VERY likely that he did) that isn't the way to do that. Depending on the publication and how they do business, there are several ways this could have unfolded. The likely process was something like this:
1. Author writes article
2. Editor reads article, and makes changes, and sends back to author
3. Author re-writes
4. Step 1-3 occur as many times as needed to get the article to where it needs to be
5. Editor (sometimes the author is in on this, but most of the time they aren't, unless they are specifically in the shot...gun reviews usually have shots of the author shooting) decides which types of pictures they want with the article.
6. Editor writes notes for photographer or illustrator on what they want. Such as, "Shooter shooting at silhouette from 5'."
7. At this point, they may use stock photos from an agency, or that they have on hand. This saves time and money. If they have a picture that is even close, they might use it (this by itself could account for the screw up). If not, it gets sent to a photographer.
8. Photographer sets up shots to match editors description.
9. After shoot, photographer submits edited photos to editor, to include in article.
10. Editor chooses the photos they think go best with the article.
In this case I outlined above, there's a good chance that the photographer didn't have the person shoot from retention. Even if the editor knows this is wrong (and likely they do) they might use the photo anyway, because of the cost of doing a re-shoot. Even using a photographer on your payroll, a single 1 hour photoshoot could cost several thousand dollars (lots depending on this, a minimum would likely be around $1000).
The best thing you could do is to write them and let them know their error. Hopefully, they'll write a correction or something in their next issue. It's always best to remember that things like this aren't always what they seem (Such as an inept author). For each article you read in a magazine, there were probably over a dozen hands on it for the different aspects, some with a lot of experience with the subject matter, some with little experience (photographers aren't hired for their knowledge of the subject matter, they're hired for their ability to take good photos).