I was trying to book flights on the AC seat sale to W. Palm Beach this summer. Not only does AC not fly there, AC also does not codeshare on UA to that destination.

To me, it does not make sense that if AC has seasonal service to some international destinations, that it does not code-share on all of these routes (if the Star Alliance partner does fly to this destination) - for those passengers who may want to go to the destination off-season. There must be some demand by Canadians to go to W Palm Beach in the summer time; otherwise, AC would not have had had full-year service to this destination last year.