I have a Mileage Plus Select card and have used the Choices to refund the cost of tix after they are purchased. Not sure if UR works like this but there is no way they could deny you PQD. You are just redeeming the credit card charge with the miles and it has to be purchased on UA.com with the Mileage Plus credit card. In fact you can do this up to 90 days after you purchase the ticket, even if you have already flown.