Looks like the DB needs ready: false on device absence or plugged in devices show up as immediately available. That's a bug, will need to investigate later.

lib/db/api.js

@@ -163,6 +163,7 @@ dbapi.unsetDeviceOwner = function(serial) {
 dbapi.setDeviceAbsent = function(serial) {
   return db.run(r.table('devices').get(serial).update({
     present: false
+  , ready: false
   }))
 }