To be found guilty, you have to have the Means and Method to be able to carry out the crime you're accused of doing/plotting. And these anarchists didn't have either until this FBI Informant came along and gave them the money (FBI Money) to buy the explosives - aka: The Means - and then find a supplier (the FBI) of the C4 for them - aka: The Methods.
Ergo, until this guy came along (acting for the FBI), this little group were just a bunch of blow-hards spouting off the typical anarchist bull___.
Caveat: I'm not an attorney but I have played one in court.
Hey, hey, hey it is all in the name of safety and security, so it is all good right.