The link between Mozart, geometry, and morality was a theme at the time when the technical people of the day worked in guilds, which formed a kind of continuity of civil society while the politics of the time played out. While he was creating music, these technical and increasingly social guilds and confraternities had recently (by decades) consolidated into the fraternal organization that became freemasonry.

e.g. https://en.wikipedia.org/wiki/Mozart_and_Freemasonry

In the OP article, that someone could find an emphasis on themes like relief and truth veiled in allegory should not be a surprise. There is a lot of depth and prior art around using geometric concepts to illustrate moral principles that goes back to Greek cults of Pythagoras and others. Is it scientific? Not really, but as a way to encode and reference knowledge, geometry is the most permanent and universally understood system in which to preserve it.

A very enjoyable article.