They used evidence of atheists versus theists on moral dilemma tests? What, are atheists an independently evolved line of humanity? No, of course not. That's a really weak basis for their argument.
The simple support to that argument is that religion, currently and historically hasn't shown itself to be moral. Therefore there is likely little connection between morality and religion. You need basic morality to form societies, and you need societies to form religions. Hence morality comes first.
Hmmm, not finding that article via the link in the OP.
But Atheists vs. Theists in moral dilemma tests makes sense to me. The general claim is that Atheists are amoral. The cop-out argument to one's god being correct over all others is "Well, as long as you believe in something..."
Bullshit.
From the OP tagline given, I'm guessing this article found that religion tends to grow out of morality, not the other way around? Which makes a lot of sense to me.
The pair point to experiments such as the online "Moral Sense Test", for example, which show no differences between religious and atheist answers to moral dilemmas. As a result, the pair suggest that, "most, if not all, of the psychological ingredients that enter into religion originally evolved to solve more general problems of social interaction and subsequently were co-opted for use in religious activities."