There are a lot of 'serious' offences that don't involve hurting people. A few high-school nerds 'plot' to blow up the moon, no big deal. A few disgruntled people 'plot' to blow up a bridge = prison.

The FBI get's away with charging people with Pre-crime for attacks that probably would not have happened.

It's an old tactic. Angry, but non violent people can challenge the system. But, add an Agent Provocateur and you can flip things around so they seem like they are the problem.

PS: Also, the coercion / inducement line get's tricky. https://en.wikipedia.org/wiki/Milgram_experiment