Arthur wouldn't be able to claim that he had done the family a favor of Brian was eliminated. So it would be a loss to him too.
After he was done stomping the resistance out of Brian, he said to him, "At least you didn't cave in beg for mercy. You remained stubborn until the bitter end. That is commendable."
Then he said to the crowd of onlookers, "Who is next?"
No one stepped forward. Some people even shook their heads to show just how much they didn't want to resist him.
He nodded when he saw their behavior, "Good. Now hand over what I asked for."
He began to walk away from Brian. On the way back, he said, "Don't try to play games with me. Don't waste my time, or you will regret it."
"I am a reasonable person. If you give me what I want, there won't be any trouble. But if you try to resist, you won't even be able to receive what he just received. I will eliminate you immediately."