The whole reason unaloaq succeed was because raiko had to be a dumbass and not back up the avatar when she asked for help- the second time the first time it was war with some county that did not involve republic city but the second time vattu was the issue if raiko had said yes and unalaq had to deal with an entire damn army on his doorstep i doubt vattu wouldn't have ripped ravva out of korra atleast. and maybe even have stopped vattu from merging with unalaq in the first place.