In chapter 12 of Lord of the Flies, why was Ralph ultimately saved?

I don't think that Golding was concerned if Ralph was saved or not. His point was made. THese kids failed in his little experiment. THe ending is Golding's Deus ex machine or "God in the machine". Ralph most certainly would have died were it not for the miraculous appearance of the officer. Perhaps Golding wanted to leave a glimmer of hope despite humanities inherent sickness.