Goodbye. The best thing that you can do is tell him to stop drinking and then make yourself unavailable as a soft landing pad for his failures. He needs to make new friends in a sober lifestyle. He associates you with his drinking life. I know it sounds harsh but I've been there ... on both sides.
The drunk will often transfer the reponsibility for quitting to the friend. The support system/friendship will eventually crumble under the strain and the drunk will be alone. AA and other support systems are no secret, if the drunk really wants to quit he knows where to go. If he makes it, it will be because he wants to. So skip the babysitting make the drunk face the cold hard world from the beginning. It will save time and heartache.
I’m not sure I understand your advice. Are you saying that a sober person who has a friend ask for help in quitting should turn around and shun them? If so, I completely disagree.