I'm somewhat bemused by the entire thing - as effectively they're just going "look, memetic drift imitates genetic drift!" - which isn't really all that surpris

I'm somewhat bemused by the entire thing - as effectively they're just going "look, memetic drift imitates genetic drift!" - which isn't really all that surprising. If you want to propagate a gene through a population - start with an isolated group, let them breed, then unleash them on the wider population. This is how stuff like lactose tolerance got going. If you want to propagate a meme through a population... you get the picture.