This "debunking" oversimplifies the situation by only looking at individual charged particles.
In reality, after this thing has been running for a bit, you'll have a cloud of free electrons ahead of the craft and a cloud of protons behind the craft. As protons ahead of the craft are decelerated by the leading positive plate, they will eventually slow to a low enough energy to combine with the free electrons, becoming neutral hydrogen. Only when they get inside the capacitor field will the voltage differential be great enough to re-ionize the hydrogen, at which point the electron will be shot forward to replenish the free electron cloud, while the proton will be accelerated out the back. Analogously, free electrons approaching from the rear will lose enough energy to recombine with the trailing protons, again becoming neutral hydrogen which no longer contributes to drag.
It's really no different than if you had a purely mechanical funnel scooping up neutral hydrogen and using that as fuel for a conventional ion-engine.
In reality, after this thing has been running for a bit, you'll have a cloud of free electrons ahead of the craft and a cloud of protons behind the craft. As protons ahead of the craft are decelerated by the leading positive plate, they will eventually slow to a low enough energy to combine with the free electrons, becoming neutral hydrogen. Only when they get inside the capacitor field will the voltage differential be great enough to re-ionize the hydrogen, at which point the electron will be shot forward to replenish the free electron cloud, while the proton will be accelerated out the back. Analogously, free electrons approaching from the rear will lose enough energy to recombine with the trailing protons, again becoming neutral hydrogen which no longer contributes to drag.
It's really no different than if you had a purely mechanical funnel scooping up neutral hydrogen and using that as fuel for a conventional ion-engine.