Paradoxically, Piltdown Man didn't support evolution. Therefore, it should have been real.
So many devious paths for a creationoid to take. But if they support Piltdown, it would mean that for the first time in the sorry, shabby history of creationism, they could claim to have some actual "evidence" on their side. They wouldn't know what to do with it. Because if they had one shred of evidence, people would then ask them why they didn't have anything else. Much better to be "intellectually pure" and to have no evidence at all.