I don't think McMichaels ever intended to initiate a citizen's arrest.
(also this post is not really directed at AA leaners, but more towards McMs leaners. Of course, anyone can respond to it, but if it is regarding the boxed-in argument I won't reply to that, just because we will be talking past each other. The following remarks are working completely with the assumption that there was never an intent to attempt a citizen's arrest in the first place, or detain Arbery in any way. The McMichaels's primary aim was to keep eyes on Arbery until the cops arrived. And some of the following commentary is not new.)
A lot of McMs leaners probably wonder "Why did the McMichaels stop? They should have just kept driving."
The main reason why the McMichaels parked at that stop sign was to make it easier to turn right or left if Arbery tried to cut behind them in either direction. The reason they stopped was to wait to see which direction Arbery would go. Since Arbery was behind them, there was no guarantee that Arbery would not just start running in the opposite direction. So why not just park and wait to see where Arbery would go. The McMichaels really didn't have anywhere meaningful to continue driving at that point until it was clear which way Arbery would decide to go. If Travis would have turned right or left at the stop sign they risked losing sight of Arbery altogether. If their goal was to just to keep eyes on Arbery, then it made perfect sense to NOT keep driving but wait to see where Arbery was going to go and either turn left, right or u-turn in opposite direction.
Pro-McMs-ers may say "fair enough, but why did Travis exit with his gun? Seems like a foolish thing to do." Simple. You got Arbery running straight towards you from behind. So for safety reasons it is best to exit the vehicle armed (NOT really to show Arbery the gun) but just to have it in case Arbery were to try to attack. Also there was no guarantee that Arbery was not armed.
Early on I thought that maybe it was a bad idea for Travis to exit the vehicle with the gun. Now I think it was the right thing to do. And again if it turned out that Arbery was to cut through a yard behind them down the street right or left then all Travis had to do, based his advantageous positioning at the stop sign was to quickly slip into his truck again and slowly resume tracking Arbery. He would not have been able to do that if he had kept driving. The point of stopping was to wait on Arbery's next move.
When you break down everything the McMichael's decided to do at the stop sign, it really makes a lot of sense when you think about it.
I don't think the McMichaels ever intended to initiate a citizen's arrest at all. Neither of them looked to be in any kind of physical shape to follow through on such a thing anyway. It was all about eyes on and all about defending in case Arbery were to try to attack.