What does Isaiah 36:12 mean?

But the commander replied, 'Do you think my master sent me to say these things just to you and your king? No, it’s for everyone sitting on the wall—who, like you, will have to eat their own waste and drink their own urine.' Isaiah 36:12 - Modern Text Bible

(The commander wants everyone to hear his threats, not just the officials. He’s trying to terrify the people into surrender.)