A capable navigator heads out on a race, with his map compass but in the heat of the moment in awful conditions makes a mistake and looses his sense of direction. (How many of us has not have that happen) He gets his GPX device out of his rucksack works out where he is so he can right the situation and continue on in the race.
Has he "cheated", should he be disqualified? Would the organisers prefer him to continue floundering around on the hill or use technology to get himself back safely into the race. You could argue it is an emergency situation and the use in that situation was justified. How do you prove it really was an emergency situation? In fact who would ever know he used it, unless he owed up?

Isn't the point of a rule is that it must be enforceable.