The MCT is about what sort of connections a TA (including Aeroplan) an issue a ticket for. Once a ticket has been issued, then making sure the passenger is dealt with properly is the airline's responsibility: they have to rebook according to specific rules. So this is what they did apparently. Just what they were supposed to do.OTOH before suggesting the MCT is not realistic, one needs to consider that there may be occasions/times of the years/whatever when that MCT is perfectly fine. It is not necessarily reasonable to subject all passengers to a higher MCT forsituations that arise very occasionally.