In a statement to The Verge, OpenAI spokesperson Laurance Fauconnet strenuously denied that material from his prompts had played a role: “We can say categorically that it is impossible for Dr. Buckmaster’s Codex prompts over the last two months to have influenced the system in any way, including training.”

I think that this may actually be true. But only with the constraint of to have influenced the system. What they're not categorically denying is that they had access to these prompts and could have just based their own prompts off of that.

Yeah, I can see that. Even if the prompts didn’t directly influence the model, they could still have given OpenAI some ideas about what to explore.