As these contracts were, I'm sure, purchased on margin. They simply took the cash, having made a tidy sum for a relatively minor outlay. To have taken actual delivery, had that been the case (if they bought in at say $15 an ounce), they would have needed about 330 million dollars and a really BIG safe!
You can’t stand for delivery on a contract purchased on margin. It needs to be fully paid for, in order to stand.