1. If you think the language in Huck Finn should be changed, you are missing the point of the story. It's not simply a tale of a two runaways drifting down the Mississippi. That's just what happens in the story. What the story is about is Huck's journey to discovery that Jim is an actual human being. Huck has to defy culture, old social codes, and hundreds of years of law and tradition. True, changing the language doesn't change that story or Huck's eventual illumination. But it definitely weakens the impact of certain scenes in the novel; to be more specific I'm thinking of the scene right after Huck and Jim reunite after the fog when Huck has to "humble himself" to Jim. And I'm thinking of the scene where Huck is talking to Aunt Sally about injuries aboard a steamboat after a boiler explodes.
2. Twain's not here to defend his decision to use that language or comment on the decision to correct him as you see fit to make you feel better (see 3).
3. I suspect this is a decision to make white people feel better. We don't like that word now and we don't want to be reminded that we used to freaking LOVE it.
4. I'm not sure how to articulate this and I wish I could just send you the images in my head and a translation key for their emotional and intellectual meaning. We shouldn't soften the edges of a history we don't like to think about: we should say that yes, a long time ago, damn we were shallow and stupid and afraid and this is how we talked. This book here, this represents how we used to look at each other in all its ugliness. Twain's book is a protest against that very ugliness. His hero finally says, fuck it, I may go to hell and I may never be able to go home ever again, but I'm not going to live by these dehumanizing rules.
5. Thank you Twitter, for making me laugh about all this.
6. And to my students who had an opinion about this and could explain why (and who will likely never find this): Thank you for reading and thank you for thinking.