From the Github docs: "If you publish your source code in a public repository on GitHub, according to the Terms of Service, other users of GitHub.com have the right to view and fork your repository."

So by using GitHub, he has implicitly 'signed over' some rights to other GitHub users.

But probably not redistribute.

If, by "most jurisdictions", you mean the US and maybe Canada/Australia...

Because in "most jurisdictions" it's not actually illegal to look at things that have no license

"Checking out" something means making a copy of it, not just looking at it.

Github ToS grants some permissions