Arbery wasn't equipped in a capacity to steal and run away with anything of value from a typical construction site. At most maybe a few hand tools and some fasteners.
I'm under the impression that an armed, citizen's arrest is only for circumstances where a serious crime has been personally witnessed by the person doing the arrest. Or, if there is credible belief that a serious crime is about to be committed.
The people in the truck should've simply called 911, and given all relevant, useful information about the suspect to the dispatcher, and left it at that.
When Bubba stepped out of the truck brandishing a shotgun, he really upped the ante to a degree that did not remotely match the imagined or real crime that Arbery was suspected to have committed. Bubba SHOULD have stayed in the vehicle with the shotgun and NOT threatened Arbery with it.
With that being said, this seems very much like the Martin/Zimmerman incident a few years ago in Florida. In both individual cases a pair of idiots found each other. And in each case, one of the idiots ended up dead.
The problem is that up to that point in his life, Arbery had not done anything worthy of being killed for. Although there are likely many people that would argue that he had it coming eventually, anyways.
However, it is simply not sane, right, or legal to kill people for crimes they may commit in the future.