That's the trouble with this article, you say it's gone full Lost, you don't know that. I haven't seen the episode after this one yet, but we don't know for sure that this wasn't all just in his head. The poison may have simply not been enough to kill him, and he was hallucinating/dreaming. Leftovers is brilliant…

You really missed the point about the horse. The horse died because he started to trust again. Aaron even comments, "He always ran."