Just thought I‘d wade in here... (no pun intended). Generally an Air Detatchment is assigned to most high readiness ships (IE going to the Gulf), however, in recent times, the operational tempo has had more than one ship in the Gulf at any one time... therefore, given the lack of available Sea Kings in the first place, they are given to ships on an as required basis. Additionally, the air force has been plagued by lack of personnel as well (the Air Dets have deployed with all the ships too, they need a break). TORONTO was sent without one because there were already TWO ships there with Air Dets.
Secondly, all Canadian Warships can do vertical replenishment with helos (including MCDV‘s). The Supply ships can refuel/rearm as can the FFH‘s and DDH‘s. Generally, the supply ships don‘t sail with an Air Det since the vast majority of the ships they will service have helicopter(s) embarked and can transfer stores by vertrep anyway. There just aren‘t enough Sea Kings to go around to use one or two as replenishment platforms... they are far better off used as Over The Horizon Targeting (OTHT) platforms, the pointy end in ASW ops or, most commonly to increase the radar range of the home plate ship.
Cheers!