Ok, so add "and generate a C program to exploit it" to the prompt.

You're either being sarcastic or wildly underestimating how hard it is to write an exploit. I haven't written about exploit dev publicly for a _long_ time, but I invite you to read https://fail0verflow.com/blog/2014/hubcap-chromecast-root-pt... for what I consider to be a pretty trivial exploit of a very "squishy" (industry term) target.

XNU isn't the hardest target to pop but it is far from the easiest.

There's nobody more confident in the world, than HN poster wiring about a topic they have no experience with.

There is a huge gap (in the binary exploitation world) between identifying a problematic code pattern and having a workable bug (a reproduction), and even larger one between a reproducible crash and a working exploit (because we're not in the 90s anymore and complier/hardware mitigations are literally always enabled). Current LLMs can cross neither gap, and are not even close to bridging the second one.