Well it's their original idea and it's based on the Lobster compiler they wrote, so it isn't just a random person doing it. I'd say it's more like an expert language designer using a tool to explore an idea they otherwise wouldn't have time for.
As someone building a language with an LLM, it is exactly an exploration of curiosity. I have a lot of ideas, I don't always know how to implement them, and I certainly lack the time. The LLM can write the code, I can guide it, and I can learn what does or does not work.
