That word does not mean what you think it means. Entrapment only applies if someone is coerced to commit a crime they otherwise would not have.
In the case of the FBI's terrorism stings, the suspect was looking for allies to carry out an attack, and unknowingly contacted an undercover officer. The FBI might have supplied the "materials" and the "knowledge", but the action is all on the suspect. The FBI doesn't even swoop in for the arrest until the suspect actually tries to detonate the fake bomb.
Even in the instance of a much weaker case, where a hypothetical "radical" says "Hmm, it would be neat to blow up $building" and a hypothetical undercover officer says "Really? Well I know a guy.."
I'm finding it hard to call foul. Any sane person should recoil at the thought of indiscriminate killing and damage.