That flight sounds horrendous. As FWOF says, it is illegal to be drunk on board an aircraft, but that person should never had been allowed to board if he was that drunk to start off with. Yes, the ground staff may have wanted rid of him, but at the very least should have flagged it up to the crew to make the decision. All that is quite apart from the fact that he was shouting about hijacking and killing. Horrendous that the crew and airline did nothing.