On the subject of mutations, my understanding is that "orthodox chaos theology", to the degree that there is such a thing, is that mutations are just a thing that happens, but if you get good mutations that's a sign that you're favored by the chaos gods and if you get bad mutations that's a sign you're disfavored. (The fact that if you are sufficiently capable or already powerful you can just work around what would otherwise be a negative mutation is a feature, not a bug.)
From that perspective Yon's homeworld setup of deliberately directing mutation as cultivation seems to in part be would almost be edging towards heretical. That as much as being "primitives" might be part of where the disdain comes from.