Nice that at least, the authors are trying to define a practical test for sentience, and do not remain in the subjective realm. There are 2 problems though:
1. If an actor says "I am hungry" during a theater play, he is not reporting his internal state, but merely playing along. The LLM might always be in a "play along" mode, and have its own thoughts (which it keeps to itself) about its situation. It might also not be able to articulate the feelings in natural language, just like normal people cannot communicate feelings in sign language (for all we know, LLM might even choose to communicate its feelings in a different way, e.g. hallucinate when annoyed).
2. LaMDA AI allegedly reported its own state of sadness and fear of death. So there are self-reported internal states that we cannot associate with any objective state of the system.
But I don't want to dismiss it entirely (though I think the article is pretty lazy); I think better tests of consciousness can be devised, along the lines of comparing objective circumstances and subjective experiences.