I would venture a guess that the division of MS that issues C&D letters is probably 5 steps away from leadership at Github that could implement something like suspending your github account and removing access to repositories. THe ol' one hand doesn't talk to the other type of thing.
That being said, if you are doing something that is attracting the attention of a legal department of a Fortune 15 company, my guess is your customers would flee to competitors if they knew that.
Host your code elsewhere (gitlab?) and retain legal counsel that can help you navigate this. Asking internet strangers for advice isn't likely to be beneficial.