It simply declares that electromagnetic radiation consists of nothing but in-phase E and M fields whose intensities vary sinusoidally with time. It goes on to say that these E and M intensities are not spatial parameters, because nothing moves in any direction orthogonal to the direction of the propagating field when its intensity varies. The letter then ends. It is a mere collection of assertions, but it does show how the basic teachings of electromagnetic theory register in one's mind but then leave so much unanswered. Anyone who has a sound training in electromagnetic theory knows that when electromagnetic waves are generated by a radio transmitter there is energy that is forced into the space surrounding the transmitting antenna.
Energy is shed by that action.
They also know that energy can be received by a distant antenna which intercepts the transmitted waves. Furthermore, they know from actual experiment or from the theoretical work of Clerk Maxwell that the waves have those E and M field components. In addition, they know that, to launch the maximum amount of energy into space, those E and M wave components must set off on their journey into the depths of space by being in-phase in their time relationship. I knew that from my physics training in the mid 1940s, so Robert Hannon's message has little to say to me, other than that he does not believe there is an aether medium, or that the fields are real, but he does believe that radiation has an energy-density. So radiation from an antenna is like a gun shooting off energy-quanta at the speed of light through a medium that does not exist but is a true void.