Publishers are a business, generally speaking. To address your edit: What is the upside to a publisher of publishing a book widely (though not universally) considered offensive? Especially if that books is aimed at children?
Clearly, they consider what demand there is to be not worth the expense and potential reputational risk of satisfying. You can say that this last part is a form of censorship - but in reality, it's just how cultures work. There are things which are considered taboo. You may do them if you wish, but you have no right to say they should be consequence free.
> What is the upside to a publisher of publishing a book widely (though not universally) considered offensive?
Gosh! Now that I think of it, I honestly can't see any! Publishers are directly responsible for giving a platform to thought, and therefore, for giving that thought legs.
I only regret not thinking of this centuries ago, and using it to cen^H^H^H decide not to publish many of the things today that are considered normal, back when they were considered widely offensive!
Clearly, they consider what demand there is to be not worth the expense and potential reputational risk of satisfying. You can say that this last part is a form of censorship - but in reality, it's just how cultures work. There are things which are considered taboo. You may do them if you wish, but you have no right to say they should be consequence free.