PC got captured in that book? How? I don't even remember seeing that as a possible out come in the AP expect in book 1. The PC are supposed to being doing the capturing, not the other way around. They are evil honestly they let him Die, he is weak link. if you want to do rescue, I would just do and evil org check make them spend two of their actions, Make ruthless or surviablity checks with moderate DC of 15.
edit: their contract prevents the from feuding with each other, but does not mean they have to save him. I won't change the SP but reduce surviablity score of Organization. Say 2 or 3 points.
After they have the horn, they really should not even be going to town at all, and just defending the horn. There is no need to ever go to town you just send the minions and cohorts, and that what the old organization chapter in the back of the book is for. Also if they made friends with baron at the start, he can get them out automatically, unless they are caught in the act of preforming a murder.