Dealing with websites that primarily exist to profit from others creations isn't censorship (which is SOPA's aim).
If a real world business openly traded in stolen goods on the high street, you'd want it shut down. Even moreso if some of the goods they sold for profit were yours. You'd be effing livid if it were continuously ignored or giant loopholes allowed them to continue while you lost money.
Piracy of digital goods is no different, regardless of the weak arguments of pirates.