Why the USA is a disgrace

[Gawdzilla]

"Nations don't have friends, they have interests."

Q: Should a nation act so as to favor another nation's citizens at the expense of its own?

Rhetorical, let go of the reply button. A nation needs to take care of its people or it's not a nation. Sometimes that comes at the expense of another nation's people, unfortunate as that may be.

This is why a one government world will never work.

I'm seriously considering applying Street Epistemology with certain atheists some of the times.

A world government is not a nation. So your conclusion doesn't follow. Therefore you made an empty statement in the last paragraph.

Okay then.