Well, I know of a few, VERY few, people who are not alcoholic but are clearly headed in that direction, who quit drinking just for their own health and well-being. I would have been smart to do that, but didn't, and I wound up crossing the line eventually.
Not a darned thing wrong with quitting for health reasons. Try not to get too hung up on how he identifies himself. The Big Book is very clear that there is such a thing as heavy-drinker-headed-for-trouble-not-quite-there-but-should-quit. Very few such people do, but there are a few who do.