Javert is authoritarian, but he’s not a leader. He’s a follower of what he thinks authority dictates to him. Why? because he craves certainty. He hates having to think for himself. And submitting to authority lets him justify any cruelty he does because it must be righteous!
Russell Crowe was horribly miscast as a singing Inspector Javert, but he would’ve been incredible in a non-musical adaptation.
And that visual image of him tightrope-walking on the edge of the roof during “Stars” is cinematically perfect as a metaphor for the way he sees the world and the way he goes about it. Narrow path, not an inch to the east, not an inch to the west, no thought, no decision, just one foot in front of the other or you’re doomed and it’s your own fault.
So when Valjean puts him into a position where he suddenly has to start thinking for himself, he can’t justify who he’s been. And he can’t decide what path to follow, because he isn’t used to making decisions. He freaks out and jumps because he can’t actually process anything.
Death by cognitive dissonance.