I said I wouldn't, and I'll stick to it. Honest injun I will. People would call me a low down Ablitionist and despise me for keeping mum - but that don't make no difference. I ain't agoing to tell....Why would Huck think being called an Abolitionist would be a bad thing?
An abolitionist was someone who spoke out against slavery. The core abolitionist movement was in the Evangelical Protestant population. And like evangelists everywhere, the abolitionists wanted to tell other people what not to do. And no one likes that.
When you look at the current day, you'll still find groups evangelizing about one issue or another, and other groups objecting. Some of the current issues are Gun Control, Pro-Choice, Immigrant rights, Gay and Lesbian marriage, religious freedom, etc. Some of these issues are centuries old, like temperance. Others are relatively new, like public medicine.
Whenever you find a topic where there's not a lot of middle ground, you'll find groups using the opposing folks' name as an epithet - "You Liberal!!!"
As the Hot Button topic in the 1840s and 1850s was slavery and emancipation, and Huck lived in a slave state, it's not unexpected that he'd have been raised hearing "Abolitionist" used as a insult.
What "group names" do you find yourself using as an insult?