Given that: "SWU and EXP UDU have the same priority once the flight and associated upgrade / PALL list has passed to airport control," would an EP traveling alone ever want to keep a SWU once the upgrades have passed to airport control? Its seems like a complete waste of the SWU. Can you cancel the SWU request right before upgrades are passed to airport control?
Also, does a similar thing apply to mileage upgrades?