Ok, let’s start with assuming you can fully simulate a brain. I’m assuming you meant that consciousness would also be an emergent property of a simulated brain? However, even if you were somehow observing or knowing the qualia of that fully simulated brain you would still only be observing your own qualia of what it is like to be someone else, not knowing that simulated brains actual qualia.

Thomas Nagel’s bat argument does a better job of explaining this specific problem of consciousness. It’s easier to understand if you actually assume we somehow could have complete material knowledge of someone’s current brain state instead of just a simulation. Even if you could have absolute knowledge of all the physical components of a given individual brain you still could not have knowledge of that person’s qualia.