I have a 27 y.o. son who functions at a 9 - 15 year old level depending on the area of functionality. He also meets no one that does not warrant any and all information that he may happen to get a hold of. If it went in his head, it WILL come out his mouth.
That's just the way it is. We can train, lecture, explain, etc. and he understands and can explain it back in his own words so we know he gets it. The next day when he goes to his sheltered workshop job, if he knows it, he tells it. So, we don't store food, we buy extra when it is on sale. We keep stuff on hand for hurricanes. (The supervisors at the workshop think I am totally terrified of hurricanes.
) We explain most other things as we go because we live out in the country and it's not always easy to go to the store.
Our son is not by any means dumb, it is just there are areas that function differently. Mechanically, he can watch someone work on something and be able to work on it himself. When he gets started on a job you have to watch him or he will work until he just falls over if it is too big to do at one time. There is, however, NO filter between his brain and his mouth. So, we just make sure he has a relatively limited idea of what all we may have on hand or have the ability to do.
This young man will probably be a great worker for you. You will certainly be a great influence in his life. We learned with our son that "Presentation is everything." If, as you are getting him started on things you mention how much food it looks like you have if you buy a whole month's worth at once so you don't have to go to town very often and things like that, he may not find your food supply something worthy to remember. Competing for his mind and his mouth are going to be the tales of how he went camping, and he cleared the forest, and he helped make a place for the deer to eat, and by the time he gets through he moved the sun 4 degrees to the left.
The things that are OPSEC to you are not likely to be the things that are great stories to him, and from a surface standpoint it looks like you are just clearing virgin land.
One thing to remember to do is the varied, wandering routes to your new place. Our son still goes to sleep if the vehicle moves more than 1/2 mile, maybe your worker will too and that would make it harder for him to guide the starving droves to your place.