I believe a GPS would have caught the fact earlier that they were off course and pushed then back on course. If it had kept them on or near their course we would of never heard about the situation and they probably just spent an extra night in the woods.

They did well in in selecting a good shelter and using the local environment to its best advantage. "The couple built a snow cave, layering pine boughs on the ground and over the top of them, and huddled inside." The pine boughs where their best decision.