It also doesn't really define 'vibe code' the way that it is generally understood by developers. Lots of devs use LLMs to do the busywork parts of development without actually vibe coding. It's when you don't understand what your code does that it becomes 'vibe code' - i.e. you're relying on the vibes rather than understanding the code itself to determine if it's good enough. Under that definition, where the prompt typically isn't detailed enough to be considered a significant creative work and the person doing the prompting not only does not - but cannot - understand what it is doing, vibe code is NOT copyrightable, full stop.

If it gets included in a larger work that doesn't fit that definition, then sure, the whole is copyrightable, but then it's just chunks of vibe code, not a vibe coded product - and the contribution in the form of a pull request is not. It is public domain.