Pirate Peavey shows us the despicable side of Municipal Darwinism. Well, the whole idea is pretty despicable, Peavey just doesn't make any pretenses that it isn't.
When he captures a smaller town, he and his fellow pirates shout, "Meals on wheels!" (17.1). Peavey and the pirates show a total disregard for life, and this is how you know they're bad. Though, really, how, how different is this from Hester's misanthropy?
Well, to Hester's credit, she's only killing people who do her wrong. Peavey, on the other hand, kills indiscriminately. He even shoots a guy for his coat: "Peavey pulled out a gun and shot him dead. 'I said, give them gentleman back his COAT! [...] Sorry about the blood'" (17.42). Well, nice of him to apologize about the stain. They don't have Oxyclean in Tunbridge Wheels, so that would be really hard to get out.
Peavey isn't even nice to his own family. He has a daughter (we never see the mother) who is described as "a dim, terrified girl with watery blue eyes" (17.49). Even worse, she doesn't make very good cucumber sandwiches. Worthless.
Cucumber sandwiches—those dainty little crustless rectangles—are a big deal to Peavey, because they represent the upper crust. (Strange how the upper crust doesn't actually eat crust.) Peavey saves Tom by saying, "What I really want is to be respectable" (17.55). He thinks that Tom can teach him manners.
Even if Tom teamed up with Miss Manners, Heloise, and Dear Abby, he still wouldn't be able to teach this guy how to be a respectable human being. When Tunbridge Wheels sinks, Peavey doesn't even mourn the loss of his daughter and friends. "Little twerps! [...] I wasn't sniffling over them. It's my lovely suburb!" (20.6).
So, yeah, Peavey abandons his daughter and is then killed by his own men, suffering the least respectable death we've read in a long time. He's shot three times and sinks into muck, which "gulped him down with soft farting noises." That's pretty much all Peavey's life amounts to, a fart in a hurricane.