Again, this is not work and they are not customers.

This is somebody spending their free time on code they enjoy and then putting the result online.

The reason businesses are careful about which customers they fire is because they want to keep having customers. Open source maintainers have no reason to deal with that shit.

Then he can fire the customer. By simply closing the issue.

No this is part of the foundation that many open computing systems are built on. It's long past being just someone's experimental personal repo.

How many people have to star your repo before it's no longer yours?