I think there's a misunderstanding over what the word "relinquish" means.
The terms make clear that uploading code to GitHub gives GitHub the right to "store, archive, parse, and display Your Content, and make incidental copies, as necessary to provide the Service, including improving the Service over time" while the code is hosted on GitHub.
However, that's not the same thing as relinquishing (giving up) licensing rights to GitHub. The uploader still retains those rights, and there is nothing in the terms that says otherwise.
It is certainly a service that's being provided. If not by GitHub, then by whom?
I'll repeat the definition of service: The “Service” refers to the applications, software, products, and services provided by GitHub, including any Beta Previews.
So do you believe if you hosted a closed source project on GitHub, and GitHub decided they want to integrate this into their service they would simply be allowed to take the code?
Fortunately HN commenters are not judges. And I would wager any bet that MS lawyers would not try to argue based on their ToS either, that would be a recipe for loosing any court case.
I just mean that it doesn't really matter what your license says as long as GitHub can come up with a business justification for using it in some way. Certainly, other users still legally have to obey your copyright.
The terms make clear that uploading code to GitHub gives GitHub the right to "store, archive, parse, and display Your Content, and make incidental copies, as necessary to provide the Service, including improving the Service over time" while the code is hosted on GitHub.
However, that's not the same thing as relinquishing (giving up) licensing rights to GitHub. The uploader still retains those rights, and there is nothing in the terms that says otherwise.