The passage I find most critical to the debate:
And he [Feser] reflects on the inadequacy of materialist explanations of DNA and the genetic code, that
seem teleological through and through. Descriptions of this famous molecule make constant reference to the "information," "data," "instructions," "blueprint," "software," "programming," and so on contained within it . . ."
He then speaks of DNA as "directed toward" a sort of "goal" or "end."vii
The ID theorist might sense an ally, but Feser quickly clarifies:
It is important to note that this has nothing whatsoever to do with the "irreducible complexity" that "Intelligent Design" theorists claim certain biological phenomena exhibit; the Aristotelian need not take sides in the debate between Darwinian biologists and "Intelligent Design" theorists (who generally accept the mechanistic view of nature endorsed by their materialist opponents). Final causality is evident in DNA not because of how complex it is, but because of what it does, and would be equally evident however simple in physical structure DNA might have been.viii
I think Feser may have a point. The argument that DNA is specified may be enough to establish teleology. The argument that it is complex may establish how God did it (through secondary causes or immediately).