Yeah, it's really interesting ideas and I don't know exactly how it works. I think that it clearly had to be kept vague to leave the option open that none of it was real, and Riotus was the product of Zhen's psyche. At the end of the story it's herself she's facing down after all. But in the interpretation that it's real, I think the best we have is guesswork. I guess the two possibilities are that by the time Earth is under complete or majority Jubilite rule they have the technology to broadcast thoughts across the stars, possibly through ideas sent by Riotus? The other option, less sci-fi, is that once you are a true successor you achieve the ability to control your godhead, and through those psychic abilities you can reach other minds across the stars.

Either way, very cool, and an awesome take on space colonialism in a universe without faster than light travel.