What does it mean when someone is said to ''rust out''?

What point is the author most likely making with the example september 11

Subject: save the whales! dear professor crest, i know you are really busy and everything, but i was hoping that you could spend more time thinking about how to save the whales. it’s up to us to speak up on their behalf. it’s really wrong that some amusement parks use these poor, defenseless animals for recreational purposes. this must be stopped, and you’re the person to do it! ttyl, jules which revisions would make this e-mail more formal? check all that apply. a. removing the contractions b. removing the exclamation points c. removing the salutation d. removing the slang and casual speech e. removing the information about amusement parks

It was fifteen minutes before i could work myself up to go and humble myself to a ; but i done it, and i warn’t ever sorry for it afterwards, neither. i didn’t do him no more mean tricks, and i wouldn’t done that one if i’d a knowed it would make him feel that way. in at least one hundred words, describe what central theme in the adventures of huckleberry finn emerges in this excerpt, and how its emergence relates to the social norms of the time.