Let’s back up just a bit. John never said he thought he should have been mentioned. He said he thought he would have been mentioned. As a guy who has been a reporter and editor for more than 40 years I must say that I am surprised he wasn’t mentioned. I must also point out that your belief that a newspaper writer is going to talk to hundreds of people to gather information for a "piece there (sic) writing" is as far from the truth as it is possible to get.
It is obvious from this piece that the writer spoke with several people, but it is equally obvious that most of the information he presented relating to the origins, manufacture and recipes for the hotdogs used in the various places mentioned came from John, a recognized authority on the subject who has been the quoted source for a number of newspaper and magazine articles about hotdogs.
It is equally obvious from your post that in addition to having not the slightest idea how reporters and editors work, you also know very little about hotdogs.
Have a very nice day.