I didn’t think he died from exhaustion, I thought he made the decision to become “more powerful than you can possibly imagine” and moved to that next plane voluntarily. He was done with the crude matter of his body, and he cast it off accordingly.

Anyway, I’m fine with that ambiguity because I think it feeds into the mystery of the legend of Luke Skywalker. Different viewers are going to walk away from that with different interpretations. I’m sure the stablehand’s story at the end is pretty embellished and colored by what that kid does and doesn’t know about Luke. What you walk away with depends largely on what ideas about Luke Skywalker you’re bringing to it.