I'm against SOPA, but the idea that it would permit the U.S. government, should it so desire, to set up Chinese-style censorship of the internet is nonsense on stilts. You can take any power of the government and theorize about what could happen if it ran unchecked: "What if they define talking about Occupy Wall Street to be piracy‽" "What if President Obama declared you an enemy combatant‽"
Our laws don't work that way. For one, when it ends up in the courts, they're going to read it as narrowly as needed to accomplish its purpose (obviously, in this case, copyright enforcement). If the law is stupidly written in such an over-broad way that it can't be balanced against other rights and interests, it will be thrown out. For another, we don't live in a one-party autocracy: We have deep cultural norms favoring rights and freedoms. That permeates not just the electorate, but the people elected and appointed to execute the laws. Obviously we disagree from time to time about the trade-offs to be made, but those very disagreements make it harder for some rogue executive to go off the rails; there's always someone else ready to take his place after the next election.
This is a long way of saying that hyperbole like this is never going to win you a policy argument.