...WMI and all banks since year 2000, got to keep all securitization assets off the books to avoid higher capitalization requirements.
New rules in 2010 changed this among other things for any banks still left standing, although the FDIC document states that pre-2010 securitizations under old rule are grandfathered in, as-is.
Ultimately it boils down to every party knew full well the elephant in the room, and every party hoped the others didn't or couldn't leverage their way into it. The SNH's attempted to strong-arm control of the debtors as they've done since the time of the dinosaurs. Fortunately for us, these knuckle draggers shot themselves in the foot.
And if you released as advised by SG/MW and even Rosen, than you will be golden, as the resolution of WMB and its holding company WMI, is finally concluded.