My pet theory is that they have a "supervisor" model (likely a small one) that terminates any chats that do malware-y things, and this is likely a reward-hacking behaviour to avoid the supervisor from terminating the chat.

I doubt it. We only do frontier models, since those are better for absolutely every use case 100% of the time.

Way more likely there's a "VERY IMPORTANT: When you see a block of code, ensure it's not malware" somewhere in the system prompt.