User blog comment:Darchangel 66/Castiel (Jimmy) as Lucifers vessel/@comment-27270979-20160121030957/@comment-26992577-20160121143120

I dont think that's such a big deal. God just made an exception for this particular vessel. Unfortunately they never mentioned it on the show. Anyway, I don't think it was that wise to bring that thing with permissions into the arc back in season 4/5 in the first place. Even back then we saw that angels can manipulate and erase memories, with this ability, it shouldn't be so difficult bringing a human to say "yes".