This is what Michael Behe’s latest book, The Edge of Evolution was trying to explain.
In his observation, no new variation develops to allow natural selection to go anywhere other than within its limits. I think the author is trying to say this -— natural selection is a conservative force, not because it cannot drive novelty but because it doesn’t have the resources on which to act.
It would have been very easy for Natural selection to act as the driving force of evolution if only variations exist to drive it. The weakness of Darwinism is not natural selection but the lack of diversity in the genome to drive it anywhere.
That's nowhere in this article, and it's not remotely what the article is about.