Hmm, think of it this way. Not 'Why is the Juggernaught here' but 'Who, or what brought the Juggernaught down?'. Part of me thinks it could've run out of fuel in the desert having lost it's navigational components due to the storm, but imagining battles between these things would be awesome. On another note, Duel at Dawn seems to suggest quite a lot. I think what's implied is that, obviously, the area is a ship graveyard, with some kind of honour code stating that ships destroyed in duels are left as reminders of previous battles, and aren't stripped by folk. This could suggest the area was the site for Juggernaught battles. Again, rampant and incorrect speculation.