They can "move rooms around" between points and cash, especially a short time before the date. If it looks like it's going to be unoccupied, why not move it to points availability and move another points room over to cash. I imagine they need a supervisor's approval to do this.
60 days before a date, DVC can release unreserved rooms to CRO for cash rental. If that room is rented, the profit comes back to the members as "breakage income" in the dues statement. During that period, it can still be reserved with points.