Why shouldn't it be a topic? It still relates potentially to professional standards of behavior, which relates to ethics in an ancillary sense, at least in how you formulated it (e.g., relating to a professional's off-duty behavior). You've emphasized illegality vs. legality, I've emphasized substance use in general and how people's standards for others' behavior seem, well, subjective at times.
Some people are concerned about moderate daily alcohol use, and honestly, many people really aren't. I was merely making the point that I don't think it's a widespread view that people are concerned about this in an otherwise responsible individual simply because it takes place in a ritualized manner (say, some red wine with a meal in the evening as an established practice), although I think from what I've read about this culturally there's more concern expressed about such a practice in North America (perhaps because of our experience with alcohol prohibition and more puritanical roots in general), much less so across the pond (Spain, Italy, France, Australia, Britain).