Probably coincidence. Like the whole thing where people claim the hole in a cook pot handle is there to hole the stir spoon, or the little paper condiment cups are also some kind of saucer when pulled apart. No, it’s just the way it’s built, and plenty of pots don’t have the hole, and opening up the condiment cup is just a lucky coincidence. Also, you can bet that if the takeout container had a recommended alternate configuration it would be printed on the container to use it that way and/or you would regularly see it used that way. Any gimmick like that would be advertised to a potential customer. Not just “surprise, here’s this thing that’s been in use for 50 years and everyone’s a moron for not knowing the real use!”