Aya getting snubbed isn't the end of the world (she's not exactly crazy about butting into an incident in progress), though the fact the Moriya shrine (i.e. one of those three) doing so is quite eyebrow-raising.
I mean a shrine best known for crazy faith gathering plots NOT taking part in a faith gathering melee? And instead we have two unexpected characters taking part. This also runs counter to the building up of Sanae as a regular incident resolver in the last 2-3 games (considering the snub in TH14 in this)