But the idea that he thinks this can just stop there is preposterous, not to say revolting, actually.
The general consensus was that this theory was as offensive as it was preposterous.
To call such a scenario preposterous is to call the Internet preposterous for having already achieved that and more.
1540s, from Latin praeposterus "absurd, contrary to nature, inverted, perverted, in reverse order," literally "before-behind" (cf. topsy-turvy, cart before the horse), from prae "before" + posterus "subsequent." Related: Preposterously; preposterousness.