Perhaps but the ghosts had a hard time making it to mars. Never mind traveling to where the Fallen were some hundreds if not thousands of years ago to find a fallen to revive. The Ghosts do not need to pick a dead host to revive. In The Last Word and Thorn grimm cards it shows that a ghost did select a living host after their guardian could not be revived. So it could be a Fallen that is like Variks and understands that the ways of the Fallen are that of a dying species and they need to go back to their old ways if they are to survive.