Mexicans are being talked about because opposition to that is the same as the opposition to the ports deal. We are not willing to sell out our nation's security for economic benefits, and that's the point of difference with those who support the open border policy.
This deal wasnt about National security. However the rejection of this deal might put our security at risk because the tool of commerce might be harder to play in the region. I think this whole UAE thing has been used by people to promote a particular immigration view. It should have been kept seperate.
Those who really do want the Southern, and Northern, borders protected, thought there was more utility in keeping out the bad stuff by being able to operate abroad in the busiest ports.