What strange responses.

The more common response is that we can't make any guarantees but if you book it yourself and don't make a habit of it it doesn't seem likely anything will happen. Plans change, stuff happens. But if you do it repeatedly some airlines have started threatening to take some action. I think AC was even one of those airlines but I don't recall and I don't know if it went past a threatening letter. *and* I think it took a lot more than a single instance *and* it was revenue tickets iirc. I would guess it would be much less likely it would happen with an aeroplan ticket.

The really cheeky thing would be to then call up and ask for a refund of the US taxes