Meal priority (as per standard) is extended to AC*SE customers. Where possible and feasible, some of us will follow with AC*E customers as a courtesy - and not meant to be viewed as an inconsistency.
If there are enough meals onboard, an upgraded ML*1/SE will fall into the priority pecking order.
If there are insufficient meals, it will be confirmed verbally by the gate agent and usually **possible no meal** will be written on the boarding card and/or manifest. In this case an upgraded customer where a meal shortage exists (regardless of status) will not trump a revenue booked customer in the J/C cabin. That would seem fair. It's more of an issue with flights which are double-catered from Canada. The morning flight from SEA is catered locally, and every attempt will be made to secure an extra meal.
As always, if meal choice is a burning priority, I have absolutely no issue with a customer asking if at all possible, could "A" or "B" be put aside...