I agree it isn't about the food it is about good manners.

I had a sort of similar situation a few years ago. I went to visit my dad in DC and a friend of mine volunteered to house sit and feed my animals and I would pay him. I told him to eat whatever he wanted from the fridge/freezer. I meant whatever he would like to eat "while he was at my house" not however much he could pack away to take home with him.

I was gone four days and when I returned at least ten steaks were gone from my freezer. And half my firewood was gone. If he had asked I would have given him firewood but it upset me that he just took the wood and steaks. It wasn't the steaks or the firewood per se but just that I felt used.