The page linked has a specific rule for this type of flight --

"If your travel starts in the U.S. or Canada, or you're travelling to the U.S. or Canda as your final destination, the baggage provisions selected at the origin of your entire ticket will apply throughout your journey, regardless of stopovers (Canada effective 1 April 2015)."

So apparently the baggage rule will be the one for AC, the originating segment.