I think the difference with AI ends up being that we can't necessarily assume that they have a desire to expand and "rule" their niche the way organic life does

I think the difference with AI ends up being that we can't necessarily assume that they have a desire to expand and "rule" their niche the way organic life does. AI doesn't have to care about our kind of food, nor does it necessarily have a need or desire to reproduce. When talking about sophont species eventually wiping out other sophonts due to overlapping niches, I was picturing things like encroaching on each other's habitats, competing over food sources and so on. AI probably only would care about energy and materials, but those are less concerning to something that is immortal and requires very little to live and harness resources in space. In a way, because AI would be so much more general than us, it might not have a need to exterminate competition.