Orr's art doesn't appeal to us, but given Shepard's history of lifting designs himself, this looks like a selective and self-serving application of copyright law on his part.
Shepard has issued an explanation, saying that "A gross over-simplification of the situation could lead a lazy person to think that I'm a hypocrite for pursuing Orr because, in basic terms, we both use reinterpreted appropriated imagery." A careful person might think that, too.