The Swiderians were not Neanderthals, nor does Collins claim they were. H. Neanderthalensis disappears from the fossil record, as do their tools, approximately twenty to twenty five thousand years before the Swiderians, who lived during the Early Holocene. We have no genetic evidence indicating that the Swiderians had a greater prevalence of Neanderthal ancestry than any other Early Holocene group in West Eurasia.

Collins proposes that the practice of artificial cranial deformation in Neolithic peoples was an act of reverence for their distant ancestors. This is hypothetically not impossible, but lacks an evidentiary basis and doesn't really make a lot of sense. It's kind of like if ten thousand years from now, someone proposed