Would recommend the Matt Levine write-up:
https://archive.is/44wfuIn the J&J case, the subsidiary had the right to draw at least ~$60B in order to pay off future lawsuits if the initial subsidiary's assets ran out, so there was never any real risk that it would leave suitholders unpaid. The switch into bankruptcy court is a way to arbitrate and organize the lawsuits, which was overturned because given the right to draw money from the J&J parent co the subsidiary wasn't actually at risk of bankruptcy.