That's a terrible idea. So if someone hacks my site and installs malware, my site should be taken down by the Government?
There are anti-viruses, browser plugins, and even the browsers themselves protect you from stuff like that. You don't need the Government itself to do it, and they wouldn't be any more effective anyway. They would just abuse the power.
Even those websites should be allowed. Should we provide counter measures to help the user decide of a website is legitimate or not, absolutely, but their right to exist shouldn't be tampered with.
2) Websites that are known for mallware, phishing, or otherwise going to mess you up.
As I said I don't know if SOPA is good/bad, but my point was that "I support an Open Internet" is a bit of a cop out.