That's what i was thinking. As far as the kid is concerned i would punish him for going against what I said and then talk to him LIKE AN ADULT about alcohol. Come up with a list of questiions to ask him and actually listen to what he has to say
Find out what he knows about it, what his friends are doing, what hes seen in movies, ads, TV or from adults(how its often glorified but there is another side often not seen or talked about to alcohol) what the laws say about underage drinking and how people young and old die from DUIs, but mainly the young die from alcohol poising. How DUIs can prevent him from getting a job in specific fields.
I would make it clear that no punishment from any parent or legal authority trumps trying to hide an alcohol related OD or driving drunk to try and conceal the wrong doing (call 911 if someone ODs, call me if you need a ride)
i would also cover the effects of alcohol and the first thing that goes out the window is an ability to make rational decisions. Let him know that its nothing against him but the fact is adolescent's frontal lobe(get scientific on him so he believes you and that your not just saying it to piss him off) is the decision making part of your brain and its not fully formed until your early 20's(aka 21 to drink). Throw ETOH in the mix and really bad decisions often get made...things that are life threatening. Tell him specifically that this will happen to him to try and combat the "it'll never happen to me" mentality.
Punishment doesn't do any good unless there is a lesson learned from it. Punishment for the sake of punishment, imo, is usually in vein.
the issue can sometimes be that parents only know how to punish how they were punished(beatin's etc) and aren't aware that there are more productive ways of approaching problems. No one likes to be told their methods are not right but the track record can speak for itself.
your hypothetical friend is on his own with the wife situation.