The cat is out of the bag. Anyway I doubt that this was unforeseen by the Epic team. Somebody was bound to make honest mistake with permissions sooner or later. You just cannot expect a few thousand licensees to not screw up all of the time. And once is all that is needed.

Their are lawyered up enough to prevent anyone from profiting from their IP on the major distribution channels.

Absolutely, but that doesn't make this OK. It looks intentional, the way its been committed under a single commit etc, Epic would have prevented public forking.

It is intentional. The github user has no other activity, and it's an involving conscious process to set the Unreal Engine repository to public.