An exceedingly valid point. Yang Kai has been dealing with demon saints face to face so much of late and even made one his wife, so I reckon he might have lost sight of the fact for the great emperors he's still nothing but a junior who might be useful for their plans. Yang Kai travelling to the demon land was the great emperors' plan as well. Will they have much interest in Yang Kai's plans? Who knows, but I feel it's more likely they would rather crush the demon land and all the demons if given a chance. Yang Kai failing to save the Bright Moon great emperor and having technically been demonised certainly wouldn't make them listen to Yang Kai's opinions more.