Interestingly, my receipt says
As no goods or services have been provided in connection with this gift, the full amount is deductible to the fullest extent provided by law.
I guess they are getting around the reduced tax deduction for goods and services received in connection to the donation because the charity isn't rendering the miles, Aeroplan is, so the charity is not giving anything to you in connection to the donation, and you are also donating directly to the charity and not through AC.