I agree that he certainly did not get the silver gene from a Red Orpington, but he might have gotten it from the Rhode Island Blue. Many black chickens, and at least some blue ones, do have the silver gene (the rest have gold, or gold & silver for some males.)
@Fluster Cluck Acres do you have a picture of the Rhode Island Blue that was a parent of Charcoal?
What comb type does Penguin have? Does Penguin show any silver or gold color? Those details can help check whether Penguin really does have the parents you think he does.