If anyone believes a sufficiently smart consortium of humans could exterminate 10% of humanity, that alone should be fixed by identifying the pathways through which it could be done. The existence of AI is not needed to be concerned about that possibility.

And dealing with those pathways individually would be far more productive than attempting to control the proliferation of algorithms that think, which in the long term is probably impossible. It also leaves us on far firmer scientific footing. An individual pathway - bioweapons, nuclear weapons, etc. - is far easier to reason about and accept/reject a notion of feasibility. Treating an ASI as a machine god and asserting futility in face of that god is not going to get anything done.