They could have executed him just as easily. I don't believe this happened.
Supposedly they knew it was him. How? Were they following and stalking him? If it was a happenstance, how many pieces have to fall into place for this to happen? (he's on the road, he's tailgated by people who have no reason to care about him except maybe his bumper stickers, he pulls over for them, they don't zoom ahead, he chooses not to pull ahead but to confront them in below-freezing temperatures, they actually recognize him and decide to beat him up but not too much)
Sound a bit far-fetched to you?