Where's this confidence coming from? If Apple sees it fit to prevent you (the developer) from accessing your Apple specific userbase for any reason / violation, other people seem correct in their theorization that there's nothing you can really do as the developer.
Not implementing this new "Sign in with Apple" will also probably be interpreted as not being privacy friendly by the users, a developer can't really have that either.
Pretty much the definition of being stuck between a rock and a hard place.