I think another desparate person stealing your canned goods or even a local cop doing it, is more likely than an organized effort from on high. Still, if I had bugged out, and someone was there starving, help yourself to my cans.

If I went back into the disaster zone, while it is still lawless, I'll be sneaky, packing firearms, esp. my Remington 870, and I won't be counting on any canned goods to be there waiting for me. But if things are that bad, I really do not foresee going back in.