The four types of comma interrupters are:

1.two or more adjectives preceding a noun
2.appositive
3.compound sentence
4.direct address
5.dash
6.parenthetical expressions

Ok uhh exactly why is the question here

The answer is "he was bad enough in all conscience, but the devil himself could not temp him to turn slave-trader. satirical is a synonym for sarcastic. so when the author says that tom walker could not be tempted by the devil he does not literally mean "the devil" but he means that he is too morally upright to become a slave-trader.