Apparently the biggest objection to Mark Twain's Huckleberry Finn and Tom Sawyer is that black children are horrified and traumatized when they read the n-word. I haven't heard of white children being traumatized by this word, and it didn't traumatize me when I read Huck Finn in high school. Nor have I heard of black or white children being traumatized by the words "Injun" and "half-breed."
This suggests a better solution than simply sanitizing the books of every objectionable ethnic slur in them. The publisher could develop a black edition without the words offensive to blacks and an Indian edition without the words offensive to Indians. If the books have any words offensive to whites, a white edition could exclude them.
This is a silly solution, but it points to the silliness of the proposed solution. One silly solution deserves another.
Slurs out but racism remains
The real problem isn't that Huckleberry Finn and Tom Sawyer are great books except for the ethnic slurs. Rather, they're steeped in the racism of the era. If the publisher really wanted to address this problem, it would rewrite all the racist passages. Eliminate Jim's phony dialect and superstitious ignorance and Injun Joe's murderous savagery, among other things.
This is why critics have said replacing the slurs is a slippery slope. Where do you stop if you're really trying to protect the children? Why is it wrong to expose them to racist words but not to racist ideas?
Schools have a few ways to deal with Huckleberry Finn and Tom Sawyer. The options include 1) teach kids to deal with the ugly truths in them, or 2) don't teach them until kids are mature enough to handle them. Either option seems better than using sanitized books.
For more on the subject, see Mark Twain, Indian Hater and Is Huck Finn Racist?