And it explicitly states that it does give them the right to share your code. Copilot isn't selling code; if it were, then GitHub wouldn't let you share the output of Copilot; that would destroy their market. That they allow you to share the output of Copilot with others proves that what they are selling is the service, not the output. The output is, at worst, "shared" code from Github's licensors.

They're selling the service, which is a derivative work of the code.

Which is what the licence is granting them the right to do.