How is denying a pull request the same as banning someone from forking your project? Don't you see undue power bestowed on some people here?
It's OK for admins to deny pull requests, but not OK for them to deny the right to fork the said open source project. Kind of takes the open out of the open source by doing so.
They can fork it, they just have been disinvited from using github's fork button to do so. There's nothing blocking them from downloading the source, etc.
No, because that only applies to forking a project within the Github UI. Nothing is stopping anyone from cloning a project and pushing it to their repository.