That is the least of it. You can handwave that as magic alien tech.

At one point the proton becomes a convex mirror and reflects a lot of ligth. Seting aside wether a proton streched to a macroscopic scale wolud have a forcfield strong enough to interact with ligth in that way... it remains stationary. What hapened to conservation of mpmentum? The author should have used this as the propulsion method insted of just handwaving it.