Foxes hunt vermin and rodents. If raised from a kit, it could come to trust him. It might be stand offish, but if it lived around his habitat, then it could help control the population of vermin that would be attracted by his food stores — grain, flour, dried beef, salt pork, and Hershey bars — an Alaskan staple for centuries.
Their nocturnal nature might help the man avoid attack by humans seeking to gain advantage by raiding his cabin when he is asleep. The fox could bark or yip or whatever it is that foxes do, if others with bad intentions tried to sneak up on the house, cabin, and camp sight.
While the observations made about foxes being wild, and there wasn’t any domestication attempts in the mid-20th century. But, that doesn’t preclude a natural domestication, or partial domestication by Inuits or sequences of trappers and explorers.