If AC/AE continues to offer upgrade certificates as one of the benefits of higher tier AE membership, then reasonable no. of "I" seats must be made available (in advance and last minute at the gate when there are surplus unsold business class seats) regardless of the yield management system. It's a cost of doing business. It's the cost for having such a FF programme. AC cannot have the marketing guys on the one hand promoting come fly with us, when you reach P, E, SE, you get certificates for complimentary upgrade when the yield management guys say, wait, we can sell those seats at full fare, why let someone fly in business at the price of economy!

If the certificate says with Y or M fare, one could reserve the upgrade at any time, there must be reasonable expectation to be able to do so, including sponsorship of the travel companion. Therefore, "I" should start at 2 rather than 1 as it appears to be the case for many international flights.