I am for Oryx worming his way out of his deal with the Deep. He probably Took his worm and allowed himself to fall as a means to break free and observe the final shape of the universe (possibly using Nokris as a meat suit). He has been showing Guardians a lesson in sword logic and it would make most sense if he found a way to watch as we slaughter every last race of the Darkness with our new power taken from Oryx. It makes more sense if he lives as he was the curious one and wants to see how far the now superior organisms (Guardians) can go. He also loves his sisters to the point where he attempts to kill them in their throne world, and it would make sense for him to use Guardians as a means of doing what he could not. I doubt Oryx was mad at us for killing Crota from paternal standpoint and more as a tribute loss.