If he wants to get sober he can. AA and NA are free., and AL-Anon is free for you.
His disease is talking here, and you have the choice to listen or not. His disease tells you it is drinking to detox from pills. That is not the way, and since has been thru a supervised detox before he knows that. We alcoholics are just the best actors in the world, we can execute our lines so well that everyone believes us. Nothing will "fix" an alcoholic until they have hit their bottom, not money, a job..nothing. We have to want to be sober, and find out how to live that way in order to begin our recovery journey.
Everyones bottom is different, but, the softer our landing, the harder it is to find that bottom. Until someone pulled that soft pillow out from under my butt, and I hit bottom, I didn't seek sobriety.
I am sure AA and NA have hotline numbers "he" can call if he wants help, as well as the Salvation Army. If he threatens to kill himself, call the authorities, as he has done this before, maybe more help will be available. Also Catholic Social Services in many areas can help.
Pain is the touchstone to growth...only you can decide how much more pain you can take.
Peace.