Here's what's in the T&C (bolding added is mine):
5. Payment of all applicable fees and taxes is the sole responsibility of the Aeroplan Member. All pre-collected, applicable taxes and fees must be paid by credit card when confirming any reward booking.
a) The credit card used for payment must be in the name of the Aeroplan Member or the passenger benefiting from the travel reward.
b) On behalf of Air Canada, Aeroplan may pre-collect some applicable taxes and fees at the time of confirmation. Other taxes and fees may be collected upon departure.
http://www2.aeroplan.com/terms_and_conditions.do
Under *A T & C:
•Reward ticket validity and conditions subject to Aeroplan rules and regulations.
The T & C don't explicitly state that "on behalf of [*A airline], Aeroplan may pre-collect some applicable taxes and fees ..."
To the legal folks out there - does this matter?