I would be surprised if a psychiatrist specializing in addictions mandated AA as part of "his program". I would look over this guide provided by the National Institute on Drug Abuse entitled "Principles of Drug Addiction Treatment: A Research Based Guide ":
Principles of Drug Addiction Treatment
The guide is written off of solid research and is pretty clear on a few points:
"No single treatment is appropriate for everyone. Matching treatment settings, interventions, and services to an individual's particular problems and needs is critical to his or her ultimate success in returning to productive functioning in the family, workplace, and society." and "Effective treatment attends to multiple needs of the individual, not just his or her drug abuse. To be effective, treatment must address the individual's drug abuse and any associated medical, psychological, social, vocational, and legal problems. It is also important that treatment be appropriate to the individual's age, gender, ethnicity, and culture."
The guide can be downloaded and printed in PDF format. If he would feel more comfortable, your AH could bring it in with him to the appointment with the psychiatrist to "show" him that he doesn't have to do AA in case for some reason the psychiatrist is unwilling to listen to him. However, a better course of action would be to change psychiatrists if that happens. I think a reason that people push AA is that it is long-term and free. Studies show that long-term treatment is almost a necessity for success, so if your husband is unwilling to do AA, he must be willing to do some other form of long term therapy or recovery which can take many forms and does not necessarily have to be a group.