With Torah u'Maddah, the philosophy is once we go with the secular, we study it all. We don't differentiate.
Hirsch and TIDE have been honored by gadolim for a century and a half. And results go along with it. Hirsch was enormously successful at keeping people in the fold and attracting people. TUM has successes. There are people who can handle it. But arguably the masses cannot. It has resulted in departure from the fold plus traife offshoots like Open Orthodoxy.
Some authors are known for their decadence. D.H. Lawrence is famous for writing novels that lowered moral standards. We are not talking only about his private life here but the essence of his novels. One of his most famous novels is called "Sons and Lovers." Another is called "Lady Chatterley's Lover." There is no excuse for putting Lawrence in a collection that alleges to hold a higher moral standard.
Isaac Asimov was famous for his atheism. Moreover, his parents were Torah observant. He wrote, "I am an atheist, out and out....Emotionally I am an atheist. I don't have the evidence to prove that God doesn't exist, but I so strongly suspect he doesn't that I don't want to waste my time." To give children an attachment to an atheistic Jew who left religion is very problematic.
Yet, one sees these authors in books by at least one frum publisher of children's collections. At Stern College of Yeshiva University, they study Lawrence:
3351 Modernism 3 credits
Modernist texts in English focusing on fiction and poetry from 1900-1930. An introduction to the intellectual and technological backgrounds of modernism and their relationship to modernist themes in the visual arts. Writers may include Conrad, Stein, Joyce, Lawrence, Pound, Eliot, Yeats, Hemingway, Faulkner, Fitzgerald, and Hurston.
3733 The Development of the British Novel III 3 creditsTreats twentieth-¬century experiments in fiction. Authors may include Conrad, Joyce, Lawrence, Woolf, Lessing, Byatt, Coetzee, and Rushdie.
The frum publisher features Lawrence:
And reads Asimov:
Now the material included in the books is neither illicit nor atheist. So to a large extent this comes down to a disagreement as to whether it is appropriate to include acceptable material from authors who are otherwise unacceptable. There are some people to whom all goyim are the same and as long as the material itself is acceptable it doesn't matter what else the author has done in his writing or life because really they are all traife. But I think that we can make more precise distinctions. Some authors are far worse than others and kids develop an attachment to writers.
There are plenty of authors who don't have these glaring problems, particularly if you stick to the 19th century and earlier. Dickens, Stevenson, Hawthorne, Irving, Twain. But even if you go with the 20th you have John Steinbeck who was married 3x but his novels strive for morality. Pearl S. Buck, Arthur Conan Doyle, E.B. White, Joseph Conrad, Tolkien, Rudyard Kipling, James Joyce. You have plenty of people to choose from who are less problematic than Lawrence and Asimov.
The further back you go, the better it gets. 17th century is better than 18th which is better than 19th which is far better than the 20th. As for the 21st, stay away entirely.