The reason we know this isn't entrapment is that there is no endgame. The feds do have a budget, and starting a cult in hopes it goes crazy so they can shut it down is much harder than just saying "lets blow stuff up" to a variety of people who don't immediately object to that.
Fed plants aren't that complicated. It's "wanna blow stuff up" in a place where people might be down with that, followed by isolating those who show interest, then seeing how far down the road they can get them to go, finalized by arrest. It's the same story every time, cause it's easy, and it targets exactly who they want to hit: dumb people who want to blow stuff up. Unfortunately, the tactic doesn't work against antifa, who learned from the communist party to be extremely cell centered and also very cagey about who they are exactly.
Also, as a thing about 'glowies' being obvious and stupid: That people think they are everywhere is a win in and of itself for the FBI, as it means the next time an actual extremist starts suggesting bombings, no one is going to do that as they'd figure he's a plant, he'll get ostracized from the group for being a plant, and someone will probably report him in hopes of a payoff. All three of which are wins for not having extremist violence.