It's funny, he appears to actually be buying back the loaned coin as his own customers sell them back to him, so the more he returns, the cheaper he gets it.
Do you have any evidence to suggest that Pirate is buying the debt rather than selling it? It's clearly much more in his financial interest to be selling his own debt than buying it (selling it yields him money, buying it costs him money), and I've seen no evidence to suggest that's he's taking the loss profitable route.