That is incorrect, re-watch the video
Travis McMichaels changes position, he was standing to the left (out left) of the truck between the opened truck door and the left edge of the road, like in the middle of the road. He could easily see where Arbery was going. Arbery, instead of jogging/running straight for Travis, veers to his right to pass the truck on the grass. Travis is the then shown he moved position from being in the middle of the road, to being in front of the truck to meet Arbery.
At this point, this is aggravated assault, he moved, with shot gun in hand towards his victim. However he fires at Arbery when Arbery is now in front of the truck. Arbery, with no other options then to either attack or die, wrestles for the shot gun, Travis fires shot number two off camera, we see the buck shot blast enter the frame, it was a possible “miss”, coroner rule that one blast grazed Arbery’s hand. Both move back into frame where Arbery tries to take the shotgun but Travis finishes off Arbery with a third fatal shot.
Travis may have moved in front of the truck, but Arbery wasn’t in the grass, he was still on the roadway before he “deeked” left toward Travis. He could easily have run much farther to the right of the truck and avoided both men. The father was in the bed of the pickup-if Arbery were so afraid of being shot by one of them, he could have turned around. It is impossible to see what happened in front of the truck as the two met, but Travis backed up, had his head down and didn’t look to me to be gunning for anyone.