My opinion is that completely free expression in fictionshould be legal,even if I find it morally objectionable. Freedom of speech does not remove your moral responsibility.I support freedom of speech of course,but I also support it not being absolute,as is the case now. A call for genocide should not be legal,for instance.
To mee it seems clear,that in fiction,the author has to show at least some kind of reflection around an objectionable act,or a clear stance. Otherwise you will easily endorse for example abuse,discrimination,etc.
Another issue altogether is when the author does not see the problem.For instance a lot of sexists and racists are unaware that this is what they are.And their writings will reflect this fact.