The problem is that we won't do a complete cleansing of Congress. The President, the entire House and one-third of the Senate are up for re-election in 2012. In actual practice, we might replace the President, most House members will get re-elected and most of the Senators up for re-election will get re-elected. Americans tend to be resistant to change of their own representatives for any number of reasons, even while agreeing that everybody else's representatives need to go.
About the subject of this thread: Welcome to the real world of war. Anybody who thinks we should arrest these guys who, though they WERE American citizens, have declared war on their former home country, are welcome to try. You'll find it amazingly hard to do. They're in armed camps, in this case this guy traveled in an armed convoy, they're in countries not overly friendly to the United States, if not in some kind of open conflict with us, and so on and so on.
Sometimes it's possible to arrest a low-level doofus who is trying something here, as was recently done. A guy was going to try to fly radio-controlled airplanes into the Pentagon and the Congress, and blow them up. For the purpose he tried to get 24 pounds of C4. He got found out and set up by FBI agents, as soon as they had enough proof he was arrested. But, that was in this country, a single goof who didn't plan properly and who didn't check that his suppliers actually were who they said they were. His plan was a poor one anyway, and he was sure to get busted.
