That's what the Nuvite folks told me too. Polishing won't help a scratch that'll catch a fingernail (actually it SORT of will....if you polish it several thousand times, I guess).
I sanded a few scratches on the plane when I just did the polishing, then finished it with a 1000 grit grade and then polished. There's also a few that I didn't both with sanding, that I polished, that got a little better, that I'll deal with later.