User blog comment:Victory awaits/The actual outcome of Apocalypse?/@comment-26982641-20161001101547/@comment-27669262-20161001211056

Well, agreed. Maybe Michael`s obsession with it lead him thinking he still was be able to defeat Lucifer, really. But Castiel told Dean that the only thing he would see at the cemetery was Michael killing his brother. So either Michael was still stronger or Castiel overestimated him.