I was hoping you could answer a question for me. We are going to need a house sitter for two weeks over the summer. Along with a very fair pay, do we have to have food stocked for two weeks for the house/pet sitter as well?
Nope! You've hired yourself a responsible adult person who no doubt knows how to find food so I don't think you need to do a big shop specifically for his/her benefit (especially since you made sure to note that you are paying a fair wage).
Now, it would certainly be nice to let your house sitter help himself to the perishables in your fridge that would just go to waste anyway and if you don't mind him or her dipping into your freezer or cupboard for staples, make sure to mention it.
I think the rule of thumb here is if someone is living in your house, you should assume that they'll use your kitchen goods like plates, silverware and pans so if you have any specific requirements for that stuff (like how to clean pots and pans with special equipment) then go over that stuff during your walk-through. As far as stored food like salt and olive oil and fridge leftovers, decide what you want to offer up and have a conversation about it. I'd assume that anyone staying at your home for two weeks will start by doing a grocery store run so be clear about what's ok and what's off limits.