"Six people left in the world and one of them is Bill f*cking Murray"?

It might've been answered before, but rewatched the original movie and Tallahassee says "Six people left in the world and one of them is Bill f*cking Murray" when they meet him. Wichita, Little Rock, Columbus, Tallahassee, Bill Murray. Who is the sixth? Was this line just left in even though a scene with another survivor didn't make the final cut? Or is this meant to signify Tallahassee believing someone he cares about still lives and not being able to count them out from the ranks of the living? (Okay, this might be a bit too philosophical)