I think he would fit for something in between mentor and homeless guy claiming to have been an awesome solo. Maybe just an unassuming source of knowledge, philosophy and moral codes, with a past better kept mysterious (maybe he's never even been a solo! Maybe he's just deep!). Something like a shaman, a spiritual leader of a community, but not in a sect or religious kind of way. Someone simple people from the street turn to when they need counseling. And he always talks just a little criptic.
That fits Bartender quite well too...
Oooohhh, what about a vocal UI for the Net? Or what about Dataterminals?
In fairness, if he does get a spot voicing for an in game entity, I will probably spend ages talking to them for the hell of it.