I know that nothing is set in stone yet but personally I strongly preferred the direction the original backstory to Ashes of the Singularity (as is still shown on the history section of the wiki) was headed. Where the post humans are a more antagonistic faction of the story set in a more distant future that is bent on converting all worlds and life in the galaxy to allow them to create more processing power. In my opinion this backstory was (at least for the present) far more detailed than the current one with a more philosophical feel to it.

The current backstory which lists the AI's reasoning as "She believed that the PHC was not prepared to handle the threats that lay beyond their local neighborhood of stars" and suggests "Does Haalee know something the Post-Humans do not?" feels to me like its drawing on a theme about a mysterious external threat as an explanation for the current conflict. While not explored in quite the same fashion this theme of a mysterious external threat does seem like a common theme used in other Stardock published titles, namely Galactic Civilizations II and Sins of a Solar Empire.

While I do not have anything against this as a theme, I do feel that the direction the previous backstory was headed in had a more uncharted territory feeling. Anyway that's my take on it at least.