There's a [minor] bug. :/
Sometimes, after colonising about 2 asteroids, the AI will sit with both of them on metric 500. For ages. Then, randomly, he gets going again, after a few minutes.
Not sure what causes it so far.
I've tried it a few times now. On my last attempt, I got a really good foothold and conquered almost a quarter of the galaxy. Then I got attacked in like 4 places at the same time, and ultimately got humped again. :P