
This argument is very simple: The epigenetics mechanisms are natural, and therefore they fit well within evolutionary theory. This argument draws a (false) dichotomy between vitalism and evolution. In this banal view of nature, vitalism is evolution's foil--if a mechanism isn't violating natural law, then it evolved.
In his 2005 book Before Darwin: Reconciling God and Nature, Keith Thomson uses this argument (see Science's Blind Spot for discussion). Could this be an emerging argument for evolution? If so, it demonstrates how desperate the defense has become.