The fact that photons do not have to directly hit a magnet in order to become polarized was discovered by Michael Faraday back in 1845. By passing visual light through a magnetic field, he observed polarization. This is what we call the Faraday Effect. It can be readily reproduced in laboratories, and proves that there is a direct relationship between magnetism and light.
The way this is interpreted in the physics of this book is that highly polarized zero-point photons exiting the magnet rub against the visible photons, thereby transferring some of their spin and polarization to the visible light.
The Faraday Effect can in other words be used as supporting evidence for the position that magnetism is a form of polarized light.
When photons are polarized so that they spin along the same axis and with their positive and negative orbs facing the same way, we have magnetism.