Very true.
Arbery disagrees. That's why he took off running out of the building when he became aware a neighbor knew he was in there,
You are projecting motivation to someone you don't know without enough information to actually determine that motivation. It is possible he took off running because he knew he had been seen. It is also possible that he took off running in order to resumed his run. (If it were me, he started running exactly when I would have: as soon as I was outside the building. I don't walk to the street/driveway before I start.)
Granted, it can be argued that we are also projecting a racial motivation the highwaymen who ambushed him. Regardless of their biases, they had not seen him (or footage of him) committing a crime, let alone a felony, that day. So they had no legitimate cause to confront him with a displayed weapon.
and that's why he refused to have any sort of discussion or offer any sort of explanation like "oh I was just having a look around, I'm happy to explain that to the police - sorry, I didn't realize there had been thefts or that it was a big deal."
Mr. Arbery was under no obligation to explain anything to these guys. Were I him, my strategy would have been to ignore and not respond to them. I'd continue past them just as I usually do the guys panhandling outside the grocery store. If I saw they had weapons, this would reduce my inclination to have a discussion with them.
Mr. Arbery found what he was doing to be highly suspicious indeed, so much so that he probably overestimated how much legal peril he was actually in, and decided punching and grabbing at the gun of an armed man was an acceptable risk to take in an effort to evade police contact.
Let's think about this just a little bit.
Even in an open carry state like Georgia, people do not generally walk around with guns in their hands. Open carry of a handgun, for example, usually means visibly holstered or in a pocket. From what I've read, altering you state of carry by unholstering or even lifting your shirt to display the gun more prominently could be considered assault as the display is meant to be threatening. (There is a proposed law that would make this legal in Georgia.)
Getting out of a truck to "talk to" someone with a shotgun in hand would be pretty unusual. The mere display of the gun in that situation implies a threat and could already be a felony. Especially if you are holding it with your hand on the trigger as opposed to, say slung on your back.
So even in Georgia, someone approaching you with a shotgun is already an out of the ordinary situation where someone is likely to feel threatened.
Having attempted to avoid the position of the man with the gun only to find him waiting at the front of the truck, its reasonable to perceive a life and death situation where you have to quickly decide between fight and flight. either could be the wrong answer.
Now, even if the highwaymen were not racially motivated and identified an individual rather than a generic black man, race plays into these encounters because of the experiences of the black population.
As a relatively clean cut white person, for example, when I'm pulled over by the police, my worst case expectation is that the cop may be a jerk and I'll be inconvenienced for 15 minutes. My clean cut half-Mexican stepson who doesn't smoke anything (asthma and employment concerns also, he's a bit of a smoke-nazi), however, will not be surprised to have his car searched because the cop "smells marijuana." (This has actually happened.) Therefore, police officers might legitimately appear more threatening to him. Especially if he happens to know people with worse experiences.
Now, given the racial history of Georgia, two good old boys in a pick-up truck with guns might appear more life-threatening than they would to me or you. This weighs into his choice between fight and flight.
That said, I would still fear for my life if a truck pulled up ahead of me and the drive got out carrying his shotgun. That's just not normal behavior to me.
Lastly, I know I should ignore this, but it annoys me:
The crime statistic you keep referring to without sourcing. You only mention one variable: skin color. I won't dispute that there is likely a correlation. However, I bet that there are other variables that have an actual causation effect rather than just a correlation: economic factors, family or school environments, etc. When most crime comes from low income environments and most people who live in low income environments are Martians, then it is no surprise that most criminals are Martians even though being a Martian doesn't predispose you to being a criminal.
And a big one, I suspect is expectations of others. If people expect or assume you to be a criminal or a lowlife, you are probably more likely to become a criminal or lowlife. I grew up in a town of about 35,000 people. Most crime occurred in certain parts of town. The town was all white and had a crime rate similar (or slightly worse) than neighboring, more diverse, communities of similar size.
That's pretty much all I have to say on this thread, so I'll go back to lurking.
