I think this is pretty sloppy, at least in this statement of it. Whether one or more observers can establish with confidence whether a system is running a part

I think this is pretty sloppy, at least in this statement of it. Whether one or more observers can establish with confidence whether a system is running a particular computation is not the same thing as whether the system is running that computation. The whole section about finding a mapping between physical states and 'consciousness.exe' is exactly equally as valid for 'javac' or any other program -- but we do not conclude from this that this means that actually no physical system can run javac. The author effectively makes a bait-and-switch between consciousness and the ability of external observers to identify consciousness by searching for a mapping from physical states to computation. From this view, I think we end up exactly where we were after Descartes: we can only firmly establish our own consciousness, even if consciousness is firmly computational.