Hell if I know. This was second hand bar talk. And we all know if some enterprising Kai Feng lads smelled a buck or got coached, it would be easy to make up some ‘authentic rituals.’ I haven’t looked into the claims so this is just repeating old bar talk. i’m personally pretty skeptical of the claim as it doesn’t seem plausible to me.
good documentation would help and showing a couple of generations that practice circumcision would be part of that documentation.