Physics today is not a scientific journal. I highly doubt that they get a lot of submissions. In my experience with similar publications in a different subfield

Physics today is not a scientific journal. I highly doubt that they get a lot of submissions. In my experience with similar publications in a different subfield it's typically more that the journalists/editors at those magazines think that some topic is interesting and talk to some of the more famous researchers in the field to write an article. Sometimes it's also a bit the other way around and the researchers suggest articles to editors they know. Not to publish a letter to the editor seems a very strange decision, these are very short letters and sometimes really cover some quite niche topics. Also not getting back to the author after asking him to rewrite in a different format is just bad form.