I'm not sure what point you're trying to make, but the very page you link to contradicts what you're saying. The author of this piece has made no error, you're

I'm not sure what point you're trying to make, but the very page you link to contradicts what you're saying. The author of this piece has made no error, you're just misunderstanding. As your linked page explains, "otaku" was an old honorific that became slang for anime/manga/sci-fi geeks in the 1980s. >The word is closer to "geek". How would 銃オタク (gun otaku) fit under the media umbrella of manga, anime, or video games? Because, again as your link notes, over time the term expanded beyond its original association with media to mean intense fans of anything. Hence, "gun otaku". You may want to reread your link, as you seem confused on the subject.