At first, I figured that's the explanation, but you're ignoring a more puzzling statement in the article:
> To explain how an AI-generated story written by an AI-generated person was published despite this policy, B&H says it was part of a “test” to identify and protect against such content.
> “Our editors wrote a test article in mid-November as part of their efforts to identify and protect against AI-generated content. They overlooked adding disclosure to the article indicating that it was AI-generated, which was a mistake, and did not delete the article after the test.”
> To explain how an AI-generated story written by an AI-generated person was published despite this policy, B&H says it was part of a “test” to identify and protect against such content.
> “Our editors wrote a test article in mid-November as part of their efforts to identify and protect against AI-generated content. They overlooked adding disclosure to the article indicating that it was AI-generated, which was a mistake, and did not delete the article after the test.”
This sounds... rather unconvincing.