It looks like Bostrom was on that Extropians mailing list when the EY post was written, and ChatGPT in deep research mode was unable to find earlier mentions of the thought experiment- so, it seems plausible that Bostrom was actually referencing EY in that article.
Actually, I think Yudkowsky coined it a few months prior to that article- see http://extropians.weidai.com/extropians/0303/4140.html. That’s dated March 11, 2003, wheres the Bostrom article was apparently published at a conference later in July of that year- see https://openlibrary.org/books/OL53814584M/Cognitive_emotive_and_ethical_aspects_of_decision_making_in_humans_and_in_artificial_intelligence_vo
It looks like Bostrom was on that Extropians mailing list when the EY post was written, and ChatGPT in deep research mode was unable to find earlier mentions of the thought experiment- so, it seems plausible that Bostrom was actually referencing EY in that article.