As stated in the Op... The point is to refute theistic evolutionists who claim the early church fathers believed in an old earth... they didn't.
Except theistic evolutionists don't make that claim.
The early church fathers are not the final authority on the matter either, especially concerning science.
Modern science didn't exist in their time- just because they had theological insight doesn't mean they knew all about the physical world.
Would you trust them medically over modern medicine? they believed illness and aging were due to an imbalance of bile and that disease spread through putrid smells and demonic presence- and the reason being is because, again, they kept trying to use scriptures as a basis for science.