"Capitalism need not be its stereotypical image of a brutal, exploitive sweatshop that bleeds workers and consumers dry and benefits only a tiny class of financial aristocrats and their middlemen flunkies. This is the only definition of capitalism accepted by extreme socialists."

No, this simply propaganda- it's a tooth paste commercial, it's more of a feeling than what anyone actually thinks.

"Socialism need not be its stereotypical image of a teeming hive of identical workers struggling for survival under the watchful eyes of brutal soldiers and a soulless queen. This is the only definition of socialism accepted by extreme capitalists."

I don't think anyone thinks this- it's just some weird movie. And I can't even think of queen involved with Socialism. They have all been guys haven't they?

Though I'm having problems with identifying who would be an extreme capitalists. What comes to mind is people who are stingy or very frugal with their money. So example, this kind person would regard spending money on entertainment or fancy things as wasteful/immoral or at least not wise. Or someone who thinks work is about the only good thing he or anyone can do- work defines who you are. This kind of person might think that government program that require everyone to work would be a good thing. I don't think extreme capitalists really oppose socialism. Nor does seem that extremist Socialists oppose capitalism.
I think extremist generally refer to how far they will go.
I guess another example of an extreme capitalist is someone who works hard all their life in order that their children can have a better life. And it's their children who think up all these ideas of how life could be better.

Ideologically, I think extreme capitalist are libertarians and therefore how could they like anything about socialism- if they are extreme libertarians the government running the post office is too much government involvement. I guess I'm sort of an extreme libertarian but I realize such extreme ideas are impractical. Perhaps, impractical even if people actually wanted it. Though allowing some private competition in postal service has been a good thing- more of it, might be better. [Can you imagine a govt doing FedEx type service without there being FedEx].