I have done it a few times before I got my Presidet Club membership. Now I dont need to buy a Y ticket just to see my parents or a friend connecting in LAX...

I dont think your advice was unethical... I think is a good advice, specialy for a ther to see his son for a few hours. Besides, CO is not really losing money. not even in the AUS route... they always have plenty of seats and in less then Y fare.