Normal
I've been around a lot of drunks in my day and I've found that being the sober one around a bunch of them is really irritating. I would just tell him goodbye very politely, maybe make an excuse, and then leave; walk away even if he is still talking. If he's drunk, he probably won't remember anyway and if he remembers anything it will just be that he saw you and said goodbye. Drunks aren't really thinking so we don't have to overthink how to deal with them. As long as he's friendly, you be too but then just walk away.