The DIP financing carries a higher priority claim on collateral.
Delta just jumped ahead of some other creditors.
The other creditors probably won't complain too loud because if Delta hadn't stepped up to provide the DIP then they might have got ZERO. Delta has 'em by the b@||$.

I suspect this whole thing is what lawyers call a "briefcase bankruptcy". Basically we will now see a series of pre-planned maneuvers. Its all about dumping some assets and liabilities, getting new financing and allowing Pinnacle to move forward with a new set of assets and liabilities and a new business model.