If you give humans leeway in a particular area, they will probably transgress their boundaries and abuse that right. Rather than say, you can drink X amount, it is easier to ban alcohol outright, because the risks outweigh the benefits by far. Alcohol consumption not only damages health, but it impairs your mind. Millions of families have been torn apart by alcohol abuse, so I don't see any justification for it's use. I'd rather be on the safe side, than regret it later.
[INDENT]“Do not drink the false alcohol at all, as far as it lies in your power.”
(Guru Granth Sahib, Ang 544)
“The false-minded people who drink the alcohol are the husbands of prostitutes and their thinking is stupid. But those who are imbued with the sublime essence of the Lord, O Nanak, are intoxicated with the Truth.”
(Guru Granth sahib, Ang 399)
“Those who keep association with the (strong) five desires, put the meat of a boiled chicken in one pot, and in the other pot they put alcohol. They sit around (this meat and alcohol), and amidst these (corrupt and wicked men) sits the noseless one, the shameless queen (i.e. Maya – the illusionary world). ||1||”(Guru Granth Sahib, Ang 476)
“(O Yogi!) The Perfect Lord naturally gives the cup of Truth, to the one upon whom Waheguru casts His Glance of Grace. One who trades in this Amrit, the Divine-nectar, which gives eternal spiritual life – how could he ever love the alcohol of the world? ||2||”
(Guru Granth Sahib, Ang 360)
“O Kabeer! Those mortals who consume marijuana (drugs), fish (meat) and wine (liquor) – no matter what pilgrimages, fasts and rituals they follow, they will all go to hell. ||233||
(Guru Granth Sahib, Ang 1377)
“Salok, Third Mehl: One person brings a full bottle, and another fills his cup. Drinking which, his intelligence departs, and madness enters his mind; he cannot distinguish between his own and others, and he is pushed away by his Lord and Master; One should strictly avoid this evil alcohol by drinking of which one forgets Waheguru and is punished in His Court.
(Guru Granth Sahib, Ang 554)[/INDENT]
There is no duality here, a Sikh must not touch alcohol. it's just too risky.