I think the scenario is meant to represent a particular dilemma. The dilemma is that the food will run out if ten people are eating it. To start saying people could fish, gather fruit, etc., the people might be able to escape, they might be rescued before the food runs out, etc., is missing the point. It is not meant to be a realistic scenario where there are a number of possible "escape clauses", but just a vehicle for examining various issues - in this case whether saving 8 people by "sacrificing" 2 (for the sake of "the greater good") is justifiable.
I don't know much about philosophers/philosophy. Is it primarily concerned with "ethics". I mean, in this scenario, would some philosophical schools of thought concentrate entirely on ethics while others would take a different line?