And yet, it's called the Pythagorean Theorem. In mathematics, a theory is a coherent, sizable group of results within a field of study, and should not be understood as a scientific theory, which is yet to be proven.
Also, it's not universally true as it doesn't hold in non-Euclidean geometries, so there may be resistance to calling it a law on that front.
I’m pretty sure 2015 wasn’t real. Seriously though, look into Pythagoras. The theorem was definitely not originated by him, and there’s a reasonable chance that the legend of Pythagoras is more abstract than you think.
I had guessed Aristarchus first, since he was most likely the primary influence on Copernicus' heliocentric model, and was certainly a huge influence on the correct answer. He even calculated the distance from the Earth to the Sun to as good accuracy as the answer, but 400 years earlier. Also, Aristarchus is best known as an astronomer, whereas the correct answer was primarily known as a mathematician. I don't think the correct answer is incorrect, but it might be worth considering rephrasing the hint so that it doesn't leave so much room for interpretation.
Ancient Greece is generally considered to be the bedrock foundation of Western culture, so calling its most well-known historian a liar would seem to be more anti-Western than pro.
Also, it's not universally true as it doesn't hold in non-Euclidean geometries, so there may be resistance to calling it a law on that front.
That's a head start for your next quiz on this theme.