God was the one who instituted borders, in the first place. He also instituted laws against theft and disobedience to the laws of the land. He made govts. Mexicans have their own govt., just as we have ours.
Do you have other scripture that shows God changed how he wants aliens to be treated? We have many laws that are immoral and not according to the bible. When a law is immoral we are required to try and change it.
In your view we should never try to change abortion laws.