Were people making arguments that Simon and Schuster were wrong and censoring if they decided not to publish a book? There are a LOT of books that have been written that no 'major' publisher would touch.
Yeah, that means you have to go and publish the book yourself, and print your own copies. And it means that most bookstores probably won't carry your book, and you won't reach nearly the audience that you would if you had a major publisher.
No one argues that the publishers are wrong for doing that.