Well, part of the freedom of a U.S. citizen (which these people are) is the right to be unpatriotic. However, someone needs to have a heart-to-heart with these kids about the definition of treason. I would hate to see their ignorance and folly become a big problem for the country and for them.
Islam calls for the death of any Muslim who turns from Islam. Any Muslim who decides that Mohammed is not a prophet should be killed even according to the most moderate, democratic forms of Islam. See this post for a reference:
Democracy According to Islam Islam is an ideology which is no compatible with the United States Constitution. Unless their leaders in the United States denouce this aspect of their religion. I am waiting for them to do this. www.AfghanBibles.com