I read a Grimoire that I can not find at the moment about how the Great Machine is different from the Traveler. Something about it being an imposter or something. It was in the perspective of the Fallen. Edit: I got this from the flavor text for Baron's Ambition. It reads: [quote]"To crack open that depraved Earth-Servitor. To use its secrets to reclaim the Great Machine..." —Translated from Fallen Language[/quote] So there's that. I believe it may be intentionally ambiguous for purposes of sparking peoples imagination. Also, this is a really old theory, but it just has a lot more information in it now because of what has happened in all the expansions. I think its safe to say that the Traveler is not Good, so much as Light. Even Luke Smith hesitated when asked whether or not the Traveler was Evil.