[Alneyan]

Or perhaps, just perhaps, it only works for the human if the score condition is met? (Assuming all Empires have a default politics file) And maybe the same could go for the Demand Gift option?

Alternatively, it could just be that the AI surrenders on its own when asked to surrender, instead of accepting the demand of surrender (in this case, the surrender will be carried exactly the same, so the difference would be impossible to tell). Do you know if AIs can accept to make a gift to you?