"Maybe another company can buy the assets and continue making the sweet treats. I guess they can hire the former Hostess employees, but only on the grounds that they don't unionize."
In a real, legal bankruptcy that is what would happen. Outside investors would make offers to buy the bankrupt company's assets, which would include their food plants and even existing purchase agreements from suppliers and other vendors.But they would not be bound by existing union agreements. Many of the bankrupt company's former employees would be offered jobs because they have the necessary experience, but they would have to leave their unions to get hired.