Not to be repetitive but it might not be a bluff.
Easy. Just like you, the lenders want their money. They're angry that they made concessions (a debt for equity swap) to keep the company afloat. YRC management failed to deliver the promised turnaround. Now YRC wants to ask the lenders to make more concessions and delay interest payments on the principle for a few more years. So to make a statement and an example of a poorly managed company they will be willing to punish management by refusing to refinance, cutting their losses, and taking the meager assets they can in bankruptcy court.
If the logic is good enough for an individual teamster, why isn't it good enough for the bank? Just to reiterate, they're angry. Just like the people on this board. Sometimes it makes people ignore economic returns and want to exact a little justice. But unlike most 26,000 Teamster families, the investment banks can afford to exact justice where most of us can't afford such luxuries.