It doesn't need to be. If the license isn't positively exactly permissive then you can't use it.
I guess my point is, you can't be positive that even if you're following the license in a repo you forked that the repo owner hasn't already violated someone else's license, and now transitively, so have you.
In fact, that seems to be exactly the problem shown in the tweet - someone copy-pasted the quake source and slapped a different license on it, and copilot blindly trusted the new license.