The Trumpian definitions loosely follow the green card rules for petitioning for family members.  If someone is a citizen or green card holder, they get to petition for "family members" that fall into two categories.  Basically, those get cut off at parents of the pertitioner, children of the petitioner, and sibbling's and their spouses and children. 
 There is an heirarchy of priorities among those classification.  But, that is to get a green card and emigrate. 
 It has no bearing on tourist visas, other work type visas, etc., where there is no family petition involved.  And, the key is that it is for permanent entry (green card).  Lawful permanent residency status.  So, it makes some sense that there are those numerical/distanceof familial relationship limitations.  SCOTUS used "bona fide" relationship.  Did they actually say "bona fied FAMILY relationship"?  Either way, it's a good question as to whether or not grandma and grandpa can get a tourist visa to visit grandchildren.