I don't think the claim is that no book can survive any hostile reading, but that you can always approach a book with enough hostility to ruin it.
"Of course, those who approached Ender's Game skeptically or because they were 'forced' to read it can hardly imagine their response is valid for those who read it as volunteers or with belief: No book, however good, can survive a hostile reading."
You probe his definition by asking, If someone reads it skeptically but voluntarily, does that count as hostile? That's a good question. I don't think we have enough information to answer it, because Card does not state how to weigh skepticism and forcedness against each other.