"Khan has become a public face against Trump’s immigration policies."

No he hasn't unless in a breath of fresh air you are reporting on your own country. Khan is a Democratic prop who has had his career restarted with all of Trump's antics. 

The public face is whatever the currently running clip of an illegal immigrant mother being thrown in the back of a law enforcement car while her baby is left on the sidewalk screaming. 
The two hardworking illegal MS-13 fellows who kidnapped two young girls and tortured one to death is barely mentioned in the media.