Is SET not used in a situation like this, where a truth that may not want to be heard or addressed may be ?
SET is useful way of communicating all the time. it will not however fix things on its own. Whatever impulse is causing him to drink is too overwhelmingly powerful it will override considerations for the effect of others.
Having dealt with the consequences of severe alcoholism all I can say is the important thing is to focus on disengaging from the consequences of it. Trying to fix/educate/debate or influence them adds to the pressure on both of you, which ultimately feeds the cause.
Building his self esteem when he is sober is important so those times create a feel good experience, then disengaging when he is drinking so it creates no feel good emotions.
On the other hand sometimes it is not always done to feel good. It is done as a form of self harm, it may be worth keeping an eye out for that motivation.