Con, Fin, or Int not often matters in this game. Options are simply given for you to chose your best stat, and stat that cannot win a persuasion usually simply is not mentioned in a dialogue options. The main thing in persuasion social ability, so maybe invest some more points in that. I won that with Fin and I win every persuasion with my Finesse, like literally 99% of times. My persuasion is 6.
