The article has a date of 1 Dec 2010...yesterday. Rep. King has no official position as a single Congressman (remember that he's in the minority even at that) that would allow him to "close" Amazon down to a user. That's the essence of the First Amendment.... a law.
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances."
However, from your article, it appears that Sen. Lieberman hasn't even talked to Amazon yet.
"Senator Joe Lieberman, chairman of the Homeland Security and Governmental Affairs Committee, said he planned to discuss the hosting of WikiLeaks with the Seattle-based Amazon.
"I will be asking Amazon about the extent of its relationship with WikiLeaks and what it and other Web service providers will do in the future to ensure that their services are not used to distribute stolen, classified information," the independent senator from Connecticut said."