Hypothetically speaking, could the first or second rider legally shot that guy, at the stop sign, after he pulled out the wrench/crowbar?
In the Army, we've got "Rules of Engagement" they're pretty specific to your theater of operations, but nothing ever prevents us from defending ourselves and our fellow Soldiers with deadly force if we feel it is justified and can prove that we felt that way. I can legally go from telling a guy to stop to firing killing shots at him because something made me nervous about his behavior.
Should the first rider have just taken off and attempted to "get away" from the nut-job in the truck. What responsibility does the lead rider have to the trail guy? Should riders consider having a contingency plan if something like this were to happen? Similar to larger group riders with trail vehicles, who stops to assist fellow riders and such. essentially, "so if some jack-ass attempts to run one us off the road, we'll get away from him as quickly and safely as possible and meet up or call each other to verify location and safety."
Truthfully I was concerned that the truck driver was going to slam on the brakes, it looked like the guy behind him was pretty close. I was thinking "if I was going to be that much of a douche, I'd have slammed on the brakes and taken out the rear guy then tagged the other jackass when he got to the stop sign" Then again, it didn't appear that he had all that much going on between the ears anyway.