Logician
I have heard the story and believe you are misapplying it. Rav Chaim had no idea the guy was going to die. Even if he knew the guy was going to die the dream had nothing to do with it as chalomos ain bo mamash. The point of his psak was he would have said chalmos ain bo mamash regardless of the result. Not that if he knew the guy was going to die he would have sent him anyway.