"The problem is, demons can be summoned from almost anywhere by the use of rituals. Even the phantom zone cannot contain a demon if it is summoned. IF we were to try and contain Lilith is such a place, her brother Lucifer would just trick one of his followers into doing the necessary ritual and summon her out. And since a ritual to summon a demon to the earth plane requires human sacrifice, I would rather not be responsible for that."
Sees Lois eyeing him.
"And in case you were wondering, no. I nor my imps require such rituals to travel. It is my unique ability to open portals to anywhere without such trappings. Every demon or angel has one unique ability that none other possess and lucky me, unrestricted travel is mine."