I did not know that
That's cool. I suppose what would have disappeared would just be the head and only the human parts. Wouldn't make sense for his cybernetic body to vanish, which is what Luke burned. I suppose one could argue that only the Jedis who appear after death disappear. To date, Qui Gonn still has not post humously reappeared, and he didn't vanish.
So....any questions in play? I got nothing.