This sounds like a great insider action to cover the fraud and mismanagement: leak the keys to the kingdom in a dark web forum, so that in the resulting commotion you can blame the hackers who had access all along and obviously made your platform fail. Something, anything that your lawyers can grasp at.
I doubt that Bankman would have sanctioned that though, since he’s already admitted to malfeasance. An insider could leak the keys and arrange for a cut of the proceeds, was my line of thinking.
Bankman would have not sanctioned it because he's got much more to lose the greater the hole is. Someone around Bankman though, that has no substantial stake in FTX and suddenly realizes he was an accessory to financial fraud, has strong incentives to burn the house down.
From a secure and audited system where only a handful of people had access and the actions of each are recorded (if we dismiss Bankman's "backdoor" for a moment), all of a sudden we have a system that was wide open to the world and raided exactly after the financial collapse. As it's easy to see, your Honor, the hackers were in the system all along, forging the so called audit trail allegedly incriminating my client; when the game was up, they pounced.