LOL, of course they could sheild it enough to allow them to live long enough to get it across the border. This false dichotomy you create is transparent.
If you want to take your toys and go home, fine by me.
But the open borders are a security breach to our antion and need to be placed under control NOW!
How much lead do you think it would take to shield a cubic foot of plutonium (which would already be very heavy to begin with) Einstein?