One of the requirements for a random thought to be an hypothesis is that it has to be falsifiable with some kind of an experiment.
What would falsify this?
You can seamlessly replace EM in your paragraph with something quantum and it'd still be sort of a reasonable thought.
Well, GP would have to define "EM fields" a little more precisely, in which case for a subset of such definitions, there would be some experiments possible - strong enough EM fields, or EM fields calibrated to specific frequencies, would then wipe out consciousness (possibly unrecoverably) without seemingly damaging the physical substrate of the brain.