WLC got this entirely wrong, as one can see from reading Churchill and Murray’s discussion paper. They argue that “theistic evolution” entails asserting that “evolution” – understood as whatever represents the prevailing or mainstream scientific account of origins – is the best (as in, closest to being true) explanation for biological diversity:
Finally, all versions of theistic evolution affirm that the complexity and diversity of life are best explained by appeal to evolutionary processes that have been operative over long periods of time, where the relevant processes include those that constitute what is often called “the modern evolutionary synthesis.” (One key process in this synthesis is natural selection, acting on random mutations. But it need not be the only important biological process.) Included in this affirmation—and implicit in what follows—is an endorsement of evolution as a very good explanation of these phenomena, and not simply the best among a rather poor set of candidates.
(page 2, my emphasis)
There’s no “if evolution is true” here. Churchill and Murray are saying evolution IS true. As the passage I’ve cited comes straight from their definition of “theistic evolution,” Meyer was correct in focusing his critique on the explanatory adequacy of textbook theory.