But being thinkable does not make it scientific. Moreover at the time of mythology there was no real science other than tools and warfare.
That is more or less what he says. The science of religion looks at what we think and then at how that effects our actions and the actions others. It doesn't spend as much time on the question of "correct" thinking, or "proper" thinking modes. Outcomes matter, like did some way of thinking lead to a population growth or loss, or did other useful information get transmitted along with the not as useful religious information.