The problem isn't just that a modern adult is living in an arena quite different from the hunter-gatherer social environment in which human beings evolved. The problem is that this adult was reared in an environment quite different from that of our ancestors. Natural selection, remember, seems to have designed a certain amount of "developmental plasticity" into us. That is, how exactly our personality develops during maturation depends—by design—on the details of the social environment in which we find ourselves. And natural selection never anticipated a developmental environment like the modern one (since natural selection doesn't anticipate things). So it's not as if, by making Temptation Island exactly like the ancestral environment, you could make it a place where people would behave as "designed" to behave. Having been reared in a modern environment, these people are already corrupted as specimens.