A frustrated pronouncement against Moab. It’s a small county, proud, lots of connection to Israel. He can see it being swallowed up by the big empires, he compares it to a baby bird thrown out of its nest, confused.
He pleads for it to restore it’s relationship with Israel, but knows it probably won’t. He tells the Israelites to shelter and comfort any Moabites who escape.
The church should still comfort the weak and downtrodden, even if they are philosophically opposed.
Their sin is pride, Isaiah’s sadness is being able to see how weak they are when they can’t or won’t themselves.
This quote in the commentary I read summed up the dilemma “Whenever pride is not broken by humility, it will have to be broken by justice.”
You sense that same dilemma in Jesus’ tears over Jerusalem, just before the people called for him to be crucified. It is the motivating sadness of Christianity.