You’re arguing from emotion on behalf of your grandchild. That’s known as a conflict of interest. You are not impartial. You’d have to recuse yourself if you were on the USSC, hearing a case upon this matter.
Why, do you suppose, are people so offended at the prospect of US military being placed under UN control? It’s the well founded fear that the best interests of our military and our country may not be the first priority of the UN. The same fear is reasonable regarding the Commander-in-Chief.
Does this child have any other form of citizenship at birth?