Let's call it what it is - stolen IP and released without permission of the author. Sure, it's good that it opens the debate as to whether that's ethical given that's essentially what the model itself is doing, but it's very clear in this instance that he's just asked for and been given a copy of source that has a clear ownership. That's about as clear cut as obtaining e.g. commercial server-side code and distributing it in contravention of the licence.
That said, the article says "Okay, prompts, great. Are they any interesting? Surprisingly... yes. As an example workflow_discovery contains a full 6-phase recipe for mining business processes out of Slack conversations, something that definitely required time and experiments to tune. It's hardcoded business logic, but in prompt instead of code."
So the article author clearly knows this prompt would be copyrighted as it wasn't output from an AI, and recognises that there would have been substantial work involved in creating it.