The locals don't tend to speak English and some don't speak French either. The people who guide him around tend to wander off and leave him on his own. His Land Rover gets stuck in the sand dunes. He even picks up a sunburn. In short he doesn't seem to be having a particularly good time of it. So when he finally reaches a hotel and finds that the man in the room next to him is dead, he happily takes on the man's identity. It certainly doesn't hurt that he shares the same first name and even looks vaguely like him too.