What every author Bostrom, Eliezer et al. seem to miss is that there will be a practical mechanism for a digital AGI taking physical control of systems out of the hands of humans. Eg. they would need to control the resources around mining or recovering the metal, then building production plants etc... So we either incrementally cede power to them, in which case in theory the humans previously controlling the systems are doing so "rationally" and thus see the AGI as better. Or the system outsmarts the humans controlling the systems in which case it is demonstrating that it is smarter.
There is a tautology here that seems to be ignored: If we create a superhuman-AGI then by default it's goals will be more universally optimal than ours. They may or may not be aligned. However the definition of term is based on the fact that it is "better" in outcome than all manner of humans.
So if we create one and it decides to maximize paperclips, then that means maximizing paperclips is more optimal goal universally than whatever humans could coordinate as a goal on our own.
If we create a subhuman-AGI then we will be able to overcome it's goals by virtue of the fact that we are still superior.
I'll go back to a very old example. An ant can't determine if building the Large-Hadron Collider is an optimal global goal - it's inscrutable to the Ant. All it knows is that it's house and all it's friends were destroyed.
If it is the case that an AGI can in fact take the physical control reigns from humans, then by definition it is smarter and will make a more optimal long term goal than we could - to the point that we probably wouldn't understand what it's doing.
I think the true concern is that we will make something that is superhuman-powerful without being superhuman-intelligent. Like the doomsday machine in Dr. Strangelove, but to me that is an altogether different question.