I think the following may be the cause:
Page 83.
"The fact that some of the creditors have contractually agreed to pay their distribution to other creditors does not mean that the Debtors are required to make payments to the senior creditors that are more than the Bankruptcy Code allows, while preserving the subordinated creditors’ claims against the estate. While the Debtors can, through a plan of reorganization, effectuate the subordination agreements by diverting payments from subordinated creditors to senior creditors"
Page 84.
"The WMI Senior Noteholders are entitled under section 726(a)(5) only to the federal judgment rate of interest from the Debtors, the same as all other unsecured creditors. To the extent that this results in them getting more or less than their contract rate of interest, it may be a matter between them and the other creditors who are parties to a subordination agreement"
H's may have to pay Seniors the difference between FJR and contract rate, and at this point not too many people know what the total pay-up amount would be.
SNH's are probably dumping H's as well.