Absolutely, Bob should go at his own pace, in the direction he sees fit. Still, I can't help but be made to feel very uncomfortable with the fact that there's a young man living in a house with an alcoholic mother, and a father who deeply, and very articulately, dislikes her.
I've been around far too long to think any of this can be kept a secret from him. So, although I think it's great that change is happening, I still feel as though a cast is being put on the broken bone, but nothing has being done to stop the bleeding.
Keep in mind. I too am the parent of an only child. I know how intense that relationship can be, and how devastating it is to the child when both of it's parents are often checked out either because of drink, or worry.
I won't tell Bob what to do, but I will say this: I started actively addressing this issue with my daughter when she was 12, and started her in Alanon/Alateen when she was 14. This is a subject we talk about a lot, and she firmly believes that facing this demon head on has saved her in countless ways.
Just my two cents. Take it or leave it.