It's not illegal to fantasize. It is illegal to attempt to blow up a bridge. Federal law is remarkably consistent on this, whether you vote Democrat, Republican, or Ron Paul.
The more worrying part of this article is the targeting of certain groups and certain ideologies. Even if this particular case wasn't entrapment, that the FBI is specifically targeting certain groups and egging them on to commit acts of violence, is undemocratic and just plain evil.