(Let’s assume for this particular conversation we are not talking about explicit novels.)
We are. Because if we weren’t talking about any novel that includes explicit material,
we’d be talking about far, far fewer books. Material may not need to be “explicit” to
be forbidden for the same reason, and there’s your undisputed explicit issur.
(I did not mention bittul Torah, and in a discussion of the
specific content of works, you shouldn’t have either.)