Author here. I think you're drawing an arbitrary distinction between "acts conscious" and "is conscious", even though in practice there is no way to distinguish between them and thus they are functionally equivalent.
I cannot prove you are not a product of a simulation I am living in, that is to say, your consciousness is nonfalsifiable to me. All I can do is look at how you turn your inputs into outputs.
If a robot can do that, too (what you call "convincing as AGI") then we must assume it is also conscious, because if we don't, we'd have a logical inconsistency on our hands. If I am allowed to safely assume you are sentient, then I must also be allowed to safely assume a robot is sentient if it can convince me, because in both cases I have no method of falsifying the claim to sentience.
Thank you for your comment! I appreciate you taking the time to share your thoughts.