According to
CBS News, the FO blew a 0.081, twice the legal limit for flying. At first the guy denied drinking at all, but then admitted he had "a drink" the night before. And apparently the business about the seat wasn't just a fabrication:
Officers were called and a short time later, Maguire was observed sitting sideways in the airplane, saying he was having trouble with his seat. The other pilot in the cockpit told authorities to "take him," according to a report.
If having a BAC of "only" 0.08 caused this guy to go sideways in his seat and piss off the captain that badly in the process, I'd say he's not a heavy drinker. That's in lightweight territory. Mug shot in the linked article. He sure doesn't look like he's in great shape, but maybe that's his normal appearance.