It's not the thing, because the thing is made of substance, not electronic impulses. No matter how hard you compute, you will never compute the simulation into a real, tangible object. The simulation and the real object are extremely, obviously distinguishable, even though they're structurally analogous.

If you could simulate a human perfectly, the simulated human would not be a human, it would be a simulated human. It's not a given that it would be subject to the same rules of ethics as real humans.