If Bain & Chiad are any indication, their missing the Aiel civil war might give him a different perspective. Bain doesn't seem to accept Rand as wholeheartedly as the other Maidens do, seemingly including a Shaido Darkfriend like Melindhra. Gaul might not have accepted or thoroughly processed the truth Rand revealed. And really, Bair's "threat" was a joke or exaggeration. Not everything is a foreshadowing. It is possible, but I would put it at highly unlikely. Perrin does not have that much to do with the Aiel or their fate, and Gaul has no leadership experience or demonstrated capacity so far, beyond heading a guard detail in Tear. He's mostly been tagging along with Perrin.

But would Chiad make a good roofmistress? Would the Wise Ones support such a marriage? Given how closely they grill prospective sisters before letting them adopt one another (which, if anything can be written off and allowed to procede as the candidates desire, a trivial extension of friendship should be), I doubt they would be so sanguine about a marriage where only one party wants the threesome, especially if your chief scenario works out. You don't want a clan chief whose marriage is a messy divorce or domestic dispute waiting to happen. Marrying a woman just to make your real object of desire happy is a dubious proposition at best.