I think that sometimes the way a meal is served might influence policies about taking left-overs with you. It also helps if there is a definition of what constitutes a meal, especially if a CCRC is on a meal allotment plan versus a declining balance arrangement, the latter using an a la carte price for each chosen item. (For example: a meal debiting a monthly allotment number is defined as one cup of soup, one salad or fruit cup, one entree, 3 sides, a roll, a beverage, and a dessert.) Are meals via table service (like a restaurant), or a cafeteria line where a server behind the sneeze bar glass transfers a requested item to a plate? In either case, the resident can probably ask for less than a full helping, but probably not more. Dining staff "controls" the size of a helping. Why couldn't a person take leftovers with them, especially if food left on a plate gets thrown out. (We're in our second CCRC. At our first, we thought a local pig farmer might want the cast-out food for slop, but no --- the Health Dept requires it be re-cooked.)
With management "controlling" the portions, what is the justification for NOT permitting the taking of left-overs? I would ask management what the "issue" is ---- Is the limit of "just one small carryout container" because of the cost of the containers? Why not have people bring their own carry-out containers? Because styrofoam can't be left in "recycle bins," they require some special steps. We try to get our styrofoam (cleaned by residents after use) accumulated somewhere (A woman who no longer drives offered her car out on the parking lot!!) then taken, by willings residents, to a place that is making bricks of some kind.
I hope residents will achieve a clear dialogue with management so you can get to the root of their edicts.