I'm not entirely unsure that the situation on Roshar isn't Hoid's fault. If Hoid has been to Braize before, and if the idea that Desolations on Roshar are caused or influenced by events on Braize is correct (seems likely), then I wouldn't be shocked if he had directly brought about this new Desolation. He's there to get something, and if he could have gotten what he wanted without a Desolation going on, he had a whole hell of a long time to do it in. He's collecting/building power of different kinds, for what is obviously an important purpose (to him at any rate), and he's definitively willing to let Roshar be destroyed to get what he needs. Depending on how specifically Mr. Sanderson is choosing to answer that question (Hoid on Braize in the specifically past tense), I can't think of a much larger RAFO than Hoid deliberately unlocking the back door for Odium to start going bananas on Roshar again, in order to prompt the appearance of a force of Honor or Cultivation that he needs for his own purposes. If Roshar gets saved in the end, that's swell and dandy. If it gets flash-fried in Hatefire, then it will have been worth it.
That seems extreme to me (Cultivation's life would be part of Hoid's ante, for one), but Hoid's bouts of solemnity are very stark and bleak, and he may be driven to do some dark things. Also I may just be completely crazy, that's not off the table.
