I can't imagine the hacker(s) contacting them to say "Hey it's me! How are you? I will send you the 100k BTC missing and I get 25k BTC back. Great deal for me!"
Yeah, the hackers reading this must have thought this is some kind of a joke.
BitFinex has nothing to bargain with. They have nothing to leverage which would bring out the hackers and probably return the stolen Bitcoins. If only they are already closing in on these persons, they could raise this offer, but they are probably clueless right now. They're probably blind as to the hackers' identity and origin and even their very own next best moves to recover what was stolen.