Zero days can go for $$$, or you can go down the bug bounty route and also get $$. The cost of the LLM would be a drop in the bucket.
When the cost of inference gets near zero, I have no idea what the world of cyber security will look like, but it's going to be a very different space from today.
Except in this case the LLM was pointed at a known-to-exist vulnerability. $116 per handler per vulnerability type, unknown how many vulnerabilities exist.
The o3 discovered a new zero day exploit, it wasn't known previously, it's not the same one found by the author.