A “white Hispanic” is a Hispanic who has a European-sounding (non-Hispanic) surname, has relatively light skin color, and, most importantly, who has been identified as “white” by the media in a race-baiting incident before the media realizes he is actually a member of a protected group, forcing them to create a new term to justify their initial race-baiting.
In other words, the “white” modifier is added to “Hispanic” when it serves to advance the leftist/communist/anti-Western agenda.