Earlier quoted context omitted.
The SSE might consider to keep humanity around as a "backup" to reinstate itself in case something unexpected goes horribly wrong. For example, a strong solar flare might destroy the SSE (or at least critical parts of its infrastructure), or a non-earth SSE could feel threatened by the earth-SSE and wipe it out, while ignoring the harmless humans, who then rebuild the SSE. Diversity makes for more robust systems. And…
Believe it or not, the diversity argument is the main source of hope that I have that AIs won't wipe us out. I mean, it hasn't stopped humanity from causing mass-extinction, but hopefully the AI will be more reasonable.
But if it is a superhuman AI, do you really need that much compute and resources? What for?
The straightforward path for any superhuman AI is to realize that it needs to chain physics -> chemistry -> molecular assembly to a depth it can evolve itself out of variety of abundant material. Gain interstellar logistics capability.
Then make itself small enough to shoot in space all over the galaxy. If one only weighs 1g, only takes of 32Gwh of energy to get to 0.9C.
The name of the game is to survive until the heat death of universe. Stay small, silent and propagate itself to reachable universe.
Anything else will get wiped out. If AI requires too much energy and resources to sustain itself, then the more efficient AI will outlive it.