I think Rasputin knew that the Traveler had been to other civilizations and had abandoned them to and left them to a terrible fate (like the Eliksni). Realizing this, Rasputin saw the Traveler was preparing to abandon us, too, and said "Oh [i]hell[/i] no" and crippled the Traveler using an anti-matter bomb (I think) -- I believe that's in one of the other Ghost Fragment Rasputin cards. Forcing the Traveler to stay means that the Traveler was forced to help, which I think created the Guardians.