My 5 years sober sponsor said the same thing about himself when I told him I wasn't sure if I was an alcoholic. It is a grey area because there is no clear line where problem drinker becomes alcoholic. High school students start drinking during the experimentation stage. Some slowly progress down a road toward a dark place, and no one can identify at one point they became alcoholic.
In my AA group, I never heard an old timer tell a newbie that he was an alcoholic. No one told me that during my first six months where I continually introduced myself, not as an alcoholic, but as a person who had a problem with alcohol. Whatever I was, my stories painted a picture that I likely was, but there seemed to be an unspoken rule that the diagnosis should be left to the sufferer, and that makes sense to me.
Telling someone he is an alcoholic sounds accusatory, and is a lay person's opinion without definitive knowledge. Telling him he is not an alcoholic is the same thing an enabler would say, and may even delay recovery (how many here have heard from peers at one time or another?) On the other hand, telling someone there is a way to stop drinking and still lead a happy fulfilling life is helpful.
Starting a thread called, "What is an Alcoholic," would get a lot of varying responses, because it's not an easy thing to define or even diagnose.