I mean, if I were the author, had put my effort and time into solving my own itch and released it as FOSS, only to receive a Cease and Desist, my itch would still probably be there, but GitHub would probably comply and close the repo.
So I'd just cease, desist, and my project would suddenly appear again in some other Git server. Surely, without my name on it, and hosted from whatever country seeming less likely to follow up on similar requests.