Tbh, I don't think it's that much. Obviously it is unhealthy, and he probably has a degree of behavioural/ psychological reliance on it which might make stopping difficult.
Is it at the level that's likely to land him in hospital dying of cirrhosis before his years? From my (sadly all too full) experience of alcoholics, we're talking a quite different order of magnitude: two or three bottles every night plus a few beers, chasers, etc, as well as much more troubling episodes of binge drinking and losing control.
Is it at the level that sets him apart from those around him? That's very personal. In my industry, no, there are a lot of people who drink like this, especially in the older age groups. Top 50% of drinkers maybe, but not top 1%. Among my friends, yes, it would be considered a lot and I think it would seem too much / slightly odd at a dinner at home or in a restaurant.
This isn't to say that it won't cause health harm, particularly if he's smaller and lighter, takes a lot of other medication, has underlying health issues etc.
How you feel about it and how he feels about it may also not be so much about the total amount as other things -- the repetitiveness of the habit, doing something you don't share, etc...?