Design Arguments Succeed Only if Classical Theism is False

Here's another argument I'm toying with that's in the same vein as several others I've discussed here previously:

Suppose some natural order (e.g., teleology in organic and non-organic structures, fine-tuning, irreducibly complex biochemical structures, etc.) is best explained in terms of intelligent design. Now if the designer is the God of classical theism, then God ultimately produced the objects of design ex nihilo, without preexisting things or stuff. But all finite concrete objects are ultimately produced from preexisting things or stuff. Therefore, some natural order is best explained in terms of intelligent design only if classical theism is false.