I cannot agree with this as it seems to me that it is splitting hairs. Morality refers to the thoughts and actions of people of course and cannot be applied to inanimate objects.
Art; but especially books do more than stimulate emotion and sensation, they present an idea and when an idea is presented there is always the potential for a lie to be told. A book never read can of course be said to have no moral or immoral value, but if it can be judged as good or bad literature then it is being read, it is acting upon its audience. Books, in that they are a continuation of their authors' thoughts and deeds can have moral, immoral, or neutral consequences. A book which tells a lie, that glorifies the despicable can inspire the people who read it to immoral acts, it can needlessly darken a spirit, and it can inspire other lies like it.
A leg trap is only steel. Cold metal may not be inherently moral or immoral but if someone set it in a path and let it capture and break a leg of a passer by that would be an immoral act. The fact that the trap itself is an inanimate object does not negate that fact. What gives books and art in general the power that it has is the fact that it can be dangerous, and it is the well written lies that present the greater danger.