It is illegal to attempt to blow up the bridge. But if you do so when led by an agent of the state, having been convinced by an agent of the state to perform the act, and with the necessary materials provided by the state, then you ought not be convicted of a crime.

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.