Anyone can ask someone to stop. It is not illegal to do so.
They weren’t just asking him to stop, they were trying to make him stop.
“Travis McMichael drove down Satilla Drive toward the intersection of Buford Road, the report said. They spotted Arbery running down Buford Road. Travis drove down Burford Road and tried unsuccessfully to cut off Arbery’s escape with the truck, the report said.
The Brunswick man then turned and started “running back in the direction from which he came,” the report said. Travis McMichael again tried without success to cut Arbery off with the truck.”