Actually, the Dr. might be very smart. Giving your ex the "chance" to do it alone gives him the power to make suggestions in the future. IF, and I stress IF, he goes back to the doc, the Dr. will be able to say "Ok, John, you tried to go it alone, maybe it's time to explore other options".
Seeing you, the EX, come to the office with him probably spoke volumes to the Dr. It told him that John was likely only doing what you wanted him to do, and had no intention of following through with any treatment plan at that time. He was simply playing a game to appease you. Someone who is on the verge of seeking recovery is usually not going to bring their ex along for the ride. I feel that this Dr. probably sensed this and acted accordingly.
The Dr. most likely is waiting for the opportunity to send "John" to AA and a psychologist, and medical testing. I am sure he has seen his share of alcoholics and knows they won't respond to help unless THEY are the ones who ask for it.
Give the doc the benefit of doubt for now, and back off. This is not your battle. You may be a casualty of the battle, but it's not your fight. Do as others have suggested and learn how to deal with an alcoholic in your life. The kids will need your strength to deal with the fact their dad is an alcoholic, and you need to learn how to respond appropriately when he is drinking. Go on with your life, let him see you manage just fine without his drama and BS, and let him and his doc figure out his problems on their own. You owe it to yourself and the kids to make the best life possible, and being around a drunk isn't one of the options for your future. Good luck and positive vibes for tackling this problem.