Say who? Did you notify the UN about these findings?
For some time you might act that way, but you are trespassing.
There is no right to cross the border, but there's loads of other rights, human and otherwise, that you still undeniably have while being at the border.
There is no international body regulating any other kind of right, despite the well-meaning intention of a number of organizations.
This may end up ugly for the USA if they try to abuse that decision. Not every country in this world is Mexico.
So you want the country the person is traveling from to impose their Will on the country they are traveling to?
Happens all the time.