The goblin could have been found in the forest west of Lumbridge, watching the portal that spawned with the release of Vorago. He watches it from behind a tree, and theorises that the Big High War God, Bandos, created the portal and is using it to come to Gielinor to stomp out all the other races. He figures that a portal made by Saradomin or Zamorak would be small, meaning that it must be Bandos. However, as gods can change their size at will, the portal's size doesn't matter. He is convinced the Big High War God will come through and use Lumbridge Castle as his throne.
The goblin speaks
The goblin speaks about how Bandos will sit on Lumbridge Castle like a throne.