They pay you and you pinky swear not to release it?
Yes. If any of this information does end up getting leaked, it kills the credibility of the ransomware group and they'll never get paid again. Sort of mutually assured destruction.
Now of course, most people don't really trust criminals anyway so the business has a pretty strong bargaining position and I believe many of the ransoms are negotiated way down.
I struggle to see how this business model would work in the first place. They pay you and you pinky swear not to release it? All you are doing by negotiating is to buy the victim time to harden their systems.
This sounds liked a failed ransomware attack. They encrypted the systems - Boeing says "no thank you, we have backups". There were no valuable zero-days to sell to GRU, so give a last ditch offer to try to salvage something.