Earlier quoted context omitted.
Why does current scientific knowledge preclude it? Is a simulation of the entire human body impossible in principle, or alternatively is it known that such a simulation won't be conscious?
Because from our current understanding, the mind is an emergent property of the brain, not some ethereal thing contained by the brain. It might be possible to create artificial consciousness, to find consciousness that occurs in different ways, but to move a human mind out of a brain, as far as we can tell, is impossible.
Not all hypotheses assert substrate-dependant epiphenomenalism, which is what you seem to be suggesting.
So our current understanding is merely that we have little clue whether it's possible. I lean towards the idea that it's possible and view the burden of proof as being on your shoulders to show why wetware as a substrate is necessary.