That WOULD be a pretty impressive reveal for Demandred, and if we haven't seen him we probably haven't seen the site of his powerbase. Your point about the Shaido is well made, though even when they abandoned virtually all their honor they still veiled before killing. Of course, they weren't intentionally serving the DO either (technically we don't even KNOW these new Aiel are, though their arrival and actions amid an attack by the Shadow heavily imply it). They could simply be Darkfriend Aiel who answered a call to arms and found themselves in Kandor, mutilating themselves along the way (you have to admit, it's more distinctive and less likely to be mimiced as a false flag than red armbands are. ) That or captured and turned male channelers are the most logical and least complicated explanations for what are otherwise a new variable casually tossed in at the very end of the next to last book.