He was a man who went to services, I'm sure and THERE the Koran was read. Also, there MIGHT have been a son or daughter who did learn to read, since most people all over the world seek BETTER lives for their children, and that son or daughter might read the Koran to the family.
Saudi Arabia made huge efforts to get their population literate. There is 100% literacy, or close to it, for their young. The older folks? Not so much.
I learned NOT to make assumptions about them. Each person was a unique individual with his own history, talents and idiosyncrasies. They treated ME well so I tried to reciprocate. It helped by not making assumptions.