They said it plainly ("dark corners that someone could use to misrepresent the goals of our project"): they just don't want to see their project in headlines about "Researchers create racist LLM!".
I am not responding to the examples, and I am not challenging the claim that famous vs not famous author does not matter, or that dead tree vs screen does not matter; I am raising the question whether it's just a quantity issue ("Just so long as they read", "entire novels worth of text").
Is it? I am not sure either way. Do you lose something by only reading chapters of a novel but never the whole story from the beginning to the end, even if you're still reading the same amount?