If he is an Emerald Club member, he can take from either (if he is Executive) or take from EA (if he is just a regular member). I've done it on Premium/Luxury reservations before if I don't like what they have to offer me. I just ask them to drop my rate to ICAR and take from one of the aisles. Not sure if it's written anywhere, but I know it's common practice, at least among FTers.