That's a clear summary of the question. I think the calculator analogy is exactly right - a simulation of certain computational processes absolutely does just instantiate those processes. We really haven't defined what mean by consciousness well enough to say whether any particular simulation of consciousness is or is not the sort of thing that can be so instantiated.

The problem, as I've said before, is that I suspect the argument about simulation is less intended to establish anything specific about consciousness and more just to reinforce a particular prior intuition about what sort of thing consciousness is.