I agree it might be helpful to ask if he's getting the support he needs.
Treatment philosophies may differ, and some things work better for some than others (for example, 12 step based programs are fairly useful and universal, though there are a few steps with which I personally struggle as I am not Christian and don't understand some of the Christian - based thought).
However, as far as the science behind addiction, in my understanding, it is all or nothing. Yes, it's expected that people in recovery will slip. But to normalise this by assigning word semantics, I think this does a disservice to the clients, to allow them to think they can have 1 drink here or there and that it won't affect their overall recovery.
We all know this is not true.