User blog comment:Blaziken rjcf/My prediction for Alpha and Omega/@comment-26982641-20160526141112/@comment-34326521-20160526144733

It's not so much fear of retribution as it is just plain shame. Same reason Metatron sacrificed himself and chose to go rescue Lucifer. God had put his trust in Metatron and Castiel, and they both let him down.