Empty seats in business class at the time of boarding does not guarantee anyone a certificate upgrade, let alone a operational upgrade - irrespective of one's Aeroplan status, irrespective of the type of economy fare paid for that seat, and irrespective of whether the Y cabin is sold out or not. Passengers who have a business class award, and are on the standby list to get the J seat on that particular flight, have priority access to that seat, even before SEs with purchased Y tickets, with certificates on hand.