How do you differentiate between the drunk who boards, is polite to the CC, straps himself in and falls asleep for the rest of the flight, and the non-drunk who has been on an extended business trip, is extremely tired, completely sober and does the same? Both have probably missed the safety briefing.........
The rowdy obnoxious drunk needs ejecting - preferably in flight, but sadly, that's not allowed- but is the sleepy, quiet, polite-when-awake one a problem?