> ...why a post-biological intelligence would even be interested in spreading across the galaxy beyond a few observation outposts.
Continuity of species against some catastrophe with a solar system scale blast radius. You can keep that train of thought out to multiple solar systems, galactic arm, galaxy, supercluster, and so on.
Continuity of species against some catastrophe with a solar system scale blast radius. You can keep that train of thought out to multiple solar systems, galactic arm, galaxy, supercluster, and so on.