That's a really deep statement about the nature of existence. A mathematical theorem exists, even if the underlying structure is not represented in reality. We know that spacetime is warped by mass distribution, and is therefore non-Euclidean. However, the Pythagorean theorem is still something that exists, despite applying only to Euclidean space.

In the same way, a Platonic solid could be said to exist, even if it isn't represented in reality.