If someone's knowledge of software licenses and distributed version control is so limited that they can't figure out a way to bypass this "block," then I'm not sure they're cut out for the rigors of video game development.
First, getting blocked on GitHub doesn't remove your access to the repository. You can still see and fork the code. You just can't comment in issues and discussions.
Second, no actual developer of Godot has been blocked. Random people harassing the contributors have been blocked.