Em said he doesn't go to environments where there's alcohol/drugs. I believe he said something like 'I just don't put myself in that environment anymore.' Good for him, he's very serious about his sobriety and it appears there were a lot of drunk people there lol. A room like that wouldn't have been fun for Mr. Sober: http://www.youtube.com/watch?v=ONKNxQeLP60
Also, he probably wanted everyone to be able to have fun without the attention on him.