Except they weren't intentionally trying to deceive anyone. They made the faulty assumption that these problems were non-trivial to solve and didn't think it was simply GPT-5 aggregating solutions in the wild.
If a purported expert in the field can is willing to credulously publish this kind of result, it's not unreasonable to assume that either they're acting in bad faith, or (at best) are high on their own supply regarding what these things can actually do.