One thing to consider is how hard an AI needs to work to break out of human dependence. There’s no point destroying humanity if that then leaves you with noone to man the power stations that keep you alive.
If limited nanofactories exist it’s much easier to bootstrap them into whatever you want, than it is those nanofactories don’t exist, and robotics haven’t developed enough for you to create one without the human touch.
I would have concerns about suitably generic, flexible and sensitive humanoid robots, yes.