Ezekiel’s ultimatum in Supernatural Season 9 Episode 3 kicked Castiel to the curb for fear of putting everyone at risk in the bunker.
I still don’t quite understand the logic, especially if Sam and Dean want to help protect their friend. It makes sense to have Castiel in close proximity rather than running out and coincidentally being able to save him from killer angels.
It’s not like the angels are going to stop, and the revelation that the spell of casting them out of Heaven is irreversible means those feathered soldiers of God are going to have plenty of time to take out their anger on the graceless Castiel. It’s going to be tough to fight back when you’ve got no powers and Sam and Dean aren’t around.