Quite an interestng story but lacks one fundamental ingredient, namely
a working model based on actual numerical data for the strengths of all
the forces and fields that would be required on the scale of
interstellar space. The models presented are essentially descriptive
only and have little in the way of actual quantity.

I'm not an astrophysicist but even I as a relative lay person on the
subject am aware that electomagnetic forces are relativey relatively
insignificant compared with gravity over interstellar or intergalactic
distances.

The author seems to be saying essentially that if you discount the
presence of dark matter you can explain the anomalies that arise from
the absence of the accompanying gravity fields with large scale
electromagnetic effects.

I'm not qualified to challenge this but I'd have thought that if this
were tenable it would be among the mainstream competitors of
cosmological (or even astronomical) theory. Electomagnetism is after
all a comparatively well understood part of nature and is easy to
experiment with. If there were any substance in the proposed theory the
verdict would have been in by now.