"entered a DUI diversion program and completed nearly all of the requirements"

And his parents entered the United States and completed none of the "requirements" to be legally in the country.

There are those who follow the laws and those who violate the laws.   

His choice was a violation of DACA status.  He was given an unauthorized chance and blew it.

 He chose to drink and drive; they chose to enter the country illegally.

Choices have consequences.