My theory:
Bob was a Terminus member. Possibly left as things got cannibalistic.. Possiibly he was sent out to trick new people into coming there. But when he met this group, he changed his mind. Could explain his alcohol addiction.
Also seems like the Terminus guy new him, using his first name casually. Could also explain why Bob was last in line at the feed trough executions. Also explains why he was pleading for their lives as the execution were happening. And why the guy referred to them capturing Bob as "cosmic justice."