[adrianN]

Even if torpedos are ineffective because they pass right through the object (which I doubt, at relativistic speeds), you might want to consider sacrificing a flagship in case someone builds an attack station the size of a moon.

[Retric]

This is space fantasy, physics conforms to the plot not the other way around. Just pick the right technobabble.

Perhaps it required someone with the right force sensitivity to pull off.

Perhaps shields normally block these attacks and they turned them down to conserve fuel.

Perhaps when going past light speed ships normally just pass right on through normal matter. What happened was a never before seen effect based on failing to reach light speed in some highly unlikely fashion.

Perhaps it is reproducible, but requires tuning the shield frequencies. So it only worked do to the long period in very close proximity.

PS: Perhaps it's just a giant plot hole and showed up because someone at ILM showed a cool demo and they had to work that visual into the movie somehow.