The man's actions are cowardly. If put in that situation it is most likely if the situation is real that you will die in any eventuality other than to win. Since the same is true of a delusion that if you win the duel is over and there is no possibility of harm comming to you then so what you won a dream fight good on you, go write a novel based on it. However to reject the entire situation out of hand and to refuse to fight is stupid, wrong or right it's going to have the same outcome if you win. There is only one problem, how if the duel is won by the man can he ever tell if it was real or not?