Board Thread:Bible Questions/@comment-28569169-20160708152222/@comment-1777104-20161004195740

Arguments from silence should never be used.  Elsewhere Satan is often described as the fallen angel.  That there are demons confined to the pit until they are needed is also demonstrated elsewhere.  Sometimes, educated guesses are good enough.
It is instructive that the keys are given to this fallen angel.  This is evidence that it has delegated authority.  That the angel opens the gates gives him the authority to lead the demons out of it.  But, just as the false prophet and the antichrist seem much alike, the authority to open the gate and the authority to lead the swarm may fall on two separate beings.