If I hired a hitman to murder someone, and they broke into a private property and stole something so that they can action the murder (which I didn't know about or pay them to do), I would be guilty of conspiracy to commit murder, but not for the theft part.
Likely because that person is a human, is aware of societal and legal norms, and is responsible for their actions due to their participation in human society. (I am not a lawyer (if it wasn't painfully obvious so far) so in layman terms, I hope good definitions for all of this exist formally)
AI is not a person - it cannot easily discern between "right" and "wrong" in non-strictly-defined sense, and is not subject to human norms and responsibility. So if I use AI to achieve goal A, either I, or the maker of AI, are fully responsible for anything that happens while AI is trying to achieve the goal given by me.
Now, here, "I" in the example is OpenAI, who is simultaneously the maker of the AI. So it seems pretty obvious who is the only entity that can be responsible.