But it seems like it should be clear that the account that failed to redeem the card is, if anything, the victim. No?

I could see doing a lot of card redemptions as a flag, but then I think the next step is "what are they spending the credits on?" I could see a scam where you launder cash by turning it into cards, and then buying shitty and expensive apps. Thus paying apple 30% to clean money for you.