Combing through the abydon_finale .stringtable and .conversation files, that line regarding the death of the Duc is part of the Aloth-related conversation tree. It does not show if Aloth's autonomy value is greater than his authority value.
I'm stuck at the same exact place as you with the other two categories won. It's immensely frustrating.
Please Obsidian, for the love of orbs, give us another option or two to win this