Agreed. The shoplifting analogy isn't even necessary, just an accurate depiction of what is so scary: "If just one user uploads copyright material to youtube, SOPA allows the government to shut down all of youtube. Even if youtube removes the material as quickly as possible."
This is similar to how I described it to my relatives as well. They know enough about Facebook to understand - I told them that if I took a picture of a painting in a gallery and posted it on my facebook wall, the government could take down all of facebook.