Here is a sentence from an article by The Economist that talks about the Saudi revolution that has recently allowed women to drive:
A more normal Saudi Arabia should moderate the Islamic world, by example and because the flow of petrodollars to zealots would slow.
The sentence structure bothers me, especially the "by example" part and the comma that precedes it. At first, I thought "by example" is some sort of a bizarre phrase that somehow makes the sentence grammatical; after googling, I am inclined to say the sentence is a mistake. Or is it not?
How should I interpret the sentence?