Well, actually this is what happened: on that faithful day, 18 cars and motorcycles were lost because of the tricky navigation (no GPS then) combined with a sand storm.
So Thierry Sabine asked his chief pilot (Michel Anglade) to stay behind and rescue them, bearing in mind some had very little water and could not last more than 1-2 days.
And it took Anglade 3 days, flying from sunrise to sunset, returning to base to refuel, and up in the air again, to find them all.
And about Mark Thatcher, his team mate was a French lady Charlotte Verney.
In the French press at this time, they said if they were lost , there might be some hidden reason
, but after a couple of days, it became obvious they were in deep trouble.
Anyway, Anglade from his heli could not spot who was on the ground, so his job was first to send a radio call to give their position, then to land to give them some water, and then to take off again to find the rest.
So, it was no lack of good judgment since he did not know who was in the car when he spotted a vehicle at the time of the radio call, plus there was this charming lady to be saved