I don't know your sitch at all but I am in year 6 of in-house MLCer (he finally filed but won't leave) and my H is an alcoholic, so I do understand about that.
I completely understand everything you are saying about not wanting him back, the trauma to you and your girls, your desire for boundaries, etc., I am at that point myself and trying to get my H out of the house by any means necessary even though I never ever wanted a divorce and still feel called to stand, just from far away from him! I am sure you do need lots of walls just to keep things safe and not crazy for you guys. We are doing visitation talks now, and my D keeps asking me if she has to stay over at H's house (if he ever moves out!) because he will be drunk at night, and what should she do then. And the court doesn't care if he is a drinker unless he hits us!
So keeping in mind that I think what you are doing makes sense and is probably necessary, I would just say in answer to your question that from my far-away vantage point of knowing nothing except how much an alcoholic hates him/herself and feels shame at who s/he is, if you told him he can only come near you if he is sober, his behavior makes a lot of sense. You and your daughters have told him very clearly that you don't accept (aka in his mind, love) him if using is part of his life; so if he is not ready to be 100% sober, it seems clear that he would feel disgusting about himself and unworthy of being near you or even calling you. And realizing that might be too painful, so he might not even be able to admit that. This is the same behavior I see in my H except that he is still turning it all on me for the most part.
Maybe if your rule was that he has to be sober when he sees you but that you do not ask about what he does when he is not with you, maybe he would be less dark.
I mean, this is MLC, so maybe not, but that's just my thought, thinking of him as the Prodigal Son who is thinking of going back to his father's house but is still a broken dirty mess.
I believe I will see the bounty of the Lord in the land of the living. Wait for the Lord with courage. Be stouthearted, and wait for the Lord.