The fact that the Github license allows forking does not mean all sources there are free to copy and use.
Github's response to this question (2013 already):
Pavlo Mykhalov @growtofill 13 Jul 2013 What license terms are applicable to a public @github project if none are specified within the project?
GitHub Support
@GitHubHelp
7:32 PM - 13 Jul 2013Replying to @growtofill @growtofill We don’t impose any licenses on repositories. You should ask the owner to apply an open source license if you want to use it.
Link:
P.S. I spoke to @ausbitbank and he removed his flag and edited his comment.