Too risky. Who knows what's hiding in their code. Might be some copylefted library or a piece of code that's been copy-pasted into the project without fully complying with the copyleft requirements. Making sure this isn't the case and/or cleaning up an abandoned project can be costly and complicated. Easier for them to just kill it.
Yeah its more like a guide.
There are also a bunch of cheat sheets from GDQuest, I find the Input one especially useful: https://school.gdquest.com/cheatsheets