The Trump campaign vaulted to the top during the 2016 primary with his hard line immigration proposals. The border wall promise was his political breakthrough.

The Trump campaign vaulted to the top during the 2016 primary with his hard line immigration proposals. The border wall promise was his political breakthrough. Immigration is the key issue for many of his voters. He has been consistently strict on immigration accordingly. The decision maker was probably just following that policy line, and then got overruled by the details. In particular I assume Trump's lawyers predicted a bruising, losing court fight.