It's a panacea
It's a panacea
It's of course possible that this paper in particular is fraudulent, but note that there is a field of research making the same basic claim as this paper, so this isn't some one off thing. A reasonable amount of people from different institutions would need to be in on it for the entire field to be fraudulent.
Alternatively, I think you may be objecting to the use of the word "truthfulness" in the abstract of the paper, because you seem to think that only human thoughts can possibly have a true or false value. I'm not actually going to object to the idea that only human thoughts can be true or false, but like the response I wrote to your koan comment, the user can interpret the LLMs output, which gives the user's thought a true or false value.
In this case, philosophically, you can think of this paper as trying to find cases where the LLM outputs strings that the user interprets as false. I think the authors of the paper are probably thinking about true or false more as a property of sentences, and thus a thing mere strings can possess regardless of how they are created. This is also a philosophically valid way to look at it, but differs from your view in a way that possibly made you think their claims absurd.