His “update” doesn’t help:

UPDATE: Duncan’s spokesman, Allen Klump, sends out this statement in response to inquiries from GreenvilleOnline.com

“Congressman Duncan was simply saying what South Carolinians already know, that securing our borders is just like securing our homes. A border with no fence is like a house with no doors, where anyone or anything can come and go as they please. Congressman Duncan believes we have to secure our borders and enforce our immigration laws. As recently as two weeks ago, the Congressman introduced a bill pointing out the need to secure our Southern border from the terrorist threat coming from Iran.

“It would be both incorrect and extremely unfortunate to assign any other meaning to the Congressman’s remarks.”

The analogy is a poor one in reality, though in his scare-mongering it’s completely expected. He’s unwilling to acknowledge the truth - most people come here for opportunity, to work, or to flee oppression.