One of two things happened, he was drunk and obnoxious so he got the attention of police. Two he was so drunk he was a danger to himself, incapable of crossing the street, walking with out falling, or passed out cold on the street. At that point the arrest gets him into a safe place where he is monitored until sober and then released with a citation. Now I have not looked for more details on this and public intoxication arrests are a pain in the *** from the cops point of view because once arrested he is yours until sober. There is also the possibility someone put something into his drink so as to be able to roll him outside the bar.