He'll flip ya...Flip ya for real...
I don't put value judgements on law/chaos like that. A person who drinks a lot may be engaging in self destructive behavior, but that doesn't stop them from honoring tradition and respecting authority. If the implication is that being a drunk is harmful to oneself, and thus bad, that would lie on the good/evil axis. Though, I view alignment mostly how the character acts in society and outside themselves. This description feels very categorical imperative....which would be a great demonstration of how Law and Chaos can be controversial.
Having had a family member go through alcoholism and get out the other side, yeah, being drunk all the time (note that I said the archetype, not the style; the former almost always actually DOES have to drink alcohol to use their powers, the latter simply uses moves which sway like a drunken person) is absolutely a Chaotic thing, and terribly self-destructive.
But there's not really much point in debating it. The fact that we disagree at all--and that both of us find it strange that the other could disagree--is ample demonstration that the thing in question isn't anything like "commonly agreed."