He realized that the Purple Flower sect was indeed helpless. So he didn't reply to her question. He simply sighed in defeat.
She saw this and said, "Stop beating yourself up. It won't change anything. The fact remains that we are weak. Therefore, we deserve this."
At this point, Green Viper wanted to explode at her. He wanted to even fight her here and now. But the calm, expressionless face that she used to look at him made him calm down.
He could see in her eyes that she didn't like their situation either. He also saw in her eyes that she wasn't going to resist if he decided to hit her.
If he decided to fight, it would be just him smashing his fists against a defenseless comrade. This pulled the fire out of his motivation for a fight.
