Yes, he's not done, not even close. He has stopped buying fifths - for now - he has stopped drinking before work - for now.
Every alcoholic would like to achieve moderation, it can't be done. Think of it like going from being a cucumber to a pickle - he can't go back to being a cucumber. Once the line is crossed in to addiction, that's it.
Addiction can be put in to remission by being sober, but only remission, he can't ever drink again if he decides he really wants to stop.
The other thing is, you don't actually know him as a sober person. An alcoholic might not drink for a day or two, or a week, but that's not the same as being really sober. Alcohol changes the brain, it takes time - at least months if not longer, for that to heal. Putting the drink down is just the first step. Then there is (or should be) an attempt at recovery - which will be ongoing for life. Living life on life's terms, being honest and figuring out how you got to where you are in the first place. That can take a lot of work and a great deal of time.
The first several months of that healing and learning can be incredibly tough.
So even if he quit drinking tomorrow (he won't), that's just the beginning.