As an example, they suggest that we no longer believe everything is composed of earth, wind, fire and water, nor do we believe that general relativity shows that the proof of the Pythagorean theorem in Euclid is wrong. Let's take these one at a time.
People have reasons for classifying things as they do.
There's a sense in which it actually does, insofar as they were engaged in an activity that today would be called physics, i.e., they were trying to find out facts about spatial relations. Admittedly he then went on to devise synthetic proofs of his theorems, but he clearly regarded his results as descriptive of actual spatial relations. In this he was mistaken. In one sense it supports the idea that physical theories have been invalidated whereas math theories have not, if we accept that Euclidean geometry has been invalidated as a physical theory but not as a mathematical theory. However, in two ways, one technical and one philosophical, it also shows how mathematical ideas have been invalidated and rejected.