BA household account should work ok for him flying AA (on non trans-Atlantic). He can get a BA credit card to start the account (for spouse as well), and use a Starwood card for extra bonuses. Redemption rates domestically for AA are basically the same, besides losing the ability to make changes to award bookings. What's the downside to this for pooling this size travel to one account for earning an award in a shorter period of time?

edit: Noticed that OP was AA Gold, so you'd just want to accrue other family members flown miles to BA to keep your AA status and gold bonus miles. With a couple credit card apps you should have yourself a BA award in no time.