The way I see it is the brother doesn’t actually care for his sister he cares because she was His, and now someone is taking away something that is his and he can’t accept that.
The brother is one of those kids that gave away a toy he had only to later go back and steal it back because it’s his.
Each of his lines sounds so selfish that I can’t but help and see him this way.
I'm still on the fence as to whether this is some perverse form of misguided affection, or if he is so narcissistic that all he cares about is the perceived image of his country. Though it could be both.