Navient is a servicer. They make sure the money gets from the borrower's account into the lender's account on time. Their revenue consists entirely of the fees paid by the lenders for providing this service.

Make radical changes that impact the servicer negatively and the lender will switch to a new servicer to manage its payment flow.

The coalition of debt holders is now stuck with shares of some underperforming servicing company that just lost a huge contract.