I've long suspected that Jean Valjean was an element in the origin of {jav} "six" to begin with. My guess is that when Dr. Okrand was trying to come up with a word for "six", the TV show "The Prisoner" came to mind, but he couldn't turn that directly into a Klingon word. But "prisoner" brought up the association with Jean Valjean (JV), hence {jav}. The later slang usage of {jav} "prisoner" might've been a glimpse into this creation process.