The guy might not be a danger to himself (aside from smacking into a wall/parked car/some other inanimate object), but you have to think about the damage he could cause to others. What if he swerves into traffic, causing a driver to swerve into the other lane or off the road into a tree as a result? People swerve to avoid animals and pedestrians all the time and get into accidents, some of them very serious. This guy could get someone killed as a result. What if he's riding in the dark while drunk? I would tend to think that if he's drunk, he may not have remembered to turn on his headlight/tailight or wear reflective clothing. Someone might not see him until it's too late and he swerves into their lane. Then he's probably going to end up dead, and the driver has to live with the fact that they killed someone with their car, whether it was truly their fault or not. What's to say the guy won't run into a pedestrian on the sidewalk and kill/injure them. It could happen. A drunk cyclist certainly has the potential to kill/injure/ruin lives. Like Lotek said, if he expects the right to use the road as does a car, he should expect the penalties that come with his irresponsible actions. In the scheme of things, it might be better that he's drunk on a bike instead of behind the wheel, but the possibility to do harm is still there. I live in NH, and always understood the law to apply to bicycles. Driver's Ed. here even explains that to students, and warns that you could be prosecuted for it. This guy needs to face up and get help.

-Moab