The hypothetical "heroic figure goes and buys last copy of a 1962 guide to Ford cars to carefully maintain it in an appropriately climate controlled library" is vanishingly unlikely. A ten or a hundred or a thousand times to one, it just goes to the trash. At least here it gets scanned by the AI company.
But that scan is never made available to us in its original form. So it getting scanned by the AI company does nothing to preserve the book.