The entire set up

i think this "faction" sought out bridges' character based on circumstance. they were likely on the hunt for another victim to frame and when a house right next door to someone who had been "wronged" by the government was up for sale, they weighed the opportunity and seized. i think bridges' character could have been any victim of extremist activity but his situation just so happened to be most available at the time: house for sale right across the street, teacher of extremist classes, son the same age as the terrorists, vulnerable family situation from his wife's death.

perhaps if a home was for sale next to someone else who who had an altercation with the government, they could have been the target instead.

even at the end, it was implied that the terrorist family was already plotting their next move.