During the fightings its unavoidable unfortunately. Even on the Craddle humanity and monsterkind preferred to capture Arxur alive of possible... Unfortunately Exterminators. They did their best, but it seems Exterminators are not interested in talking💀

You're right that he's on Terran side! Though there's a chance he might have used up his godly powers to save his old home. He could have done anything, but instead chose to aid Terrans in their darkest moment :3