My alcoholic mother lived with me for a short time. I was in my mid-20's. The rule was, you can live here if you're not drinking and you find a job. She failed that so I had to kick her out.
It was really tough but I knew for my sanity I had to do it. I was not willing to watch her kill herself right in front of my eyes, in my home.
Eventually, she got sober. She's been sober for 8 years now. I didn't think that would ever happen. Despite all I tried to do, she did not get sober because of anything I did or said.
It's a horrible position for him to be in. Sounds to me he's doing the right thing, even if it is difficult.
Has he ever looked into Alanon?