Not just a bad navigator, but utterly stupid. If they had proceeded in a southerly direction after reaching the place where Eilat is today, they would have had the oil.
Reminds me of an episode of Star Trek:TNG, in which they make use of the holodeck in order to make a group of primitive people believe they're on a journey by foot, but they're being taken to another planet.
[en.wikipedia.org]
He probably couldn’t read the hieroglyphs on his map of the Middle East that he’d picked up at the local pharomart.