He could have easily thrown that tire iron at anyone and killed them.
If you can look the police in the eyes and say beyond the shadow of a doubt you were in fear of your life than deadly force would have been justified. Distance makes no difference in threat level when someone is wielding an object that can kill a person.
But that being said the video is damning for the bikers as they made no real attempt to diffuse the situation.
When they came to the stop they could have rode off but instead they dismounted and antagonized the situation.
Looking police (or anyone else) in the eyes and earnestly stating fear for your life has nothing to do with it, as everyone has their own opinion, valid or not. (Ex: Anyone ever hear of some Zimmerman character that's been in the news recently?) As for distance not being a factor, that also comes down to opinion. Unfortunately, in terms of the law, it is only the law and the jury that truly matters in terms of the outcome. We must always remember: The law and right & wrong are not the same thing. Not the same thing at all.
Again, the riders are not without fault here anyway. Technically, they initiated the encounter by riding illegally (speeding/reckless driving, crossing lane lines, illegal passing). Technically, they continued the encounter by following the truck, stopping with the truck, dismounting and approaching the truck in a hostile manner. Technically, the driver of the truck could also argue "self defense" since he was followed and then approached in a hostile manner and outnumbered. IMHO, if the rideres had harmed the truck driver in ANY way, the law would have favored the truck driver.
Did the riders have a right to be angered about the drivers intial reaction (swerving/crowding the bike)? Yes, IMHO.
Did the riders have a valid complaint/reason to call the cops about it? Yes, IMHO.
However, as soon as the riders decided to engage by following the truck, they weakened their legal position significantly. Fortunately, they were smart enough to a) not harm the driver and b) to disengage once the driver pulled the tire iron and c) call the cops while keeping their distance.
Again, the law and what's right/wrong are not the same thing at all. It can be right as rain, but if the law says otherwise, all the right in the world won't keep you outta jail.