The guy sitting in the shade doesn't bother me. Unless he suddenly decides he wants to get in another flight before he goes home. Then he becomes far more dangerous than the guys I know with bad eyesite and fading memory who usually seem to either have a friend who stands with them or who ask for help, and usually seem to fly smaller slower trainer type planes anyway.
It only takes the equivalent of one beer to cause a measureable deterioration in reflexes and judgement. Things happen mighty fast when something goes wrong with a plane or car.
The only time I saw someone get noticeably drunk at a field, several members got him taken care of, including loading his equipment into his car, one member got his keys to drive the car to his house, and another member got him into another car so he had a ride home while the first member drove his car. He was upset while it was happening, but he had the intelligence to come back the next day and apologize for being an idiot and to thank the people who took care of him