The nonexistence of grey goo (von neumann probes) is strong prior for safe agi. AI xrisk is woo. Paperclip maximizers are p-zombies. They can't exist. Chicken littles see apocalypses on every horizon even though they dont understand the technology at all. "I can imagine this destroying the world" is their justification. Even though their "imagination" is 16x16 greyscale.
A paperclip maximiser is simply an AI with an unconstrained goal that has unintended and bad consequences for us when taken to an extreme.
It does not need to be something that could function exactly like a human without having consciousness.