My guess is that this isn't so much a question of integration as logistics. It seems to me that it would be much easier to do prioritised baggage handling in containerised holds. All of CX's planes are containerised, so they can simply hold back one container and load the priority baggage into that so it is last on, first off. I can see that this isn't so easy to do consistently at the individual bag level when the bags are going up the conveyor one by one and being manually packed into the hold as they are on the A320. Prioritisation then depends on the individuals doing the loading and unloading to look for and respect the tags.