If her parents had been identified and she was adopted out, then there may still be a question of identity and so they are no closer to knowing who she is because adoption records would be sealed and no way to know what county the adoption took place in. Up until recent decades, unwed mothers or teen mothers were often spirited away outside the county or state to give birth and deal with adoption issues.
As for genealogy—if EDJD was an only child of her mother's, there may not be anyone on her mother's side who took a test and they may not find anyone closer than say a 2nd or 3rd cousin, which makes it still difficult to pinpoint the right woman. Say her mom had 4 sisters and the mom and two sisters are deceased...if the dead sisters didn't have children, then you have 3 females who could be possible and now have to backtrack and found the link one of them may have had to the known father—a link that could be 50-55 years ago. Can anyone remember all the men their sister dated that long ago? And if it was a one night stand, almost impossible.
As for the mother's DNA being black or Native, that could be, but there are still enough of those populations that the DNA would at least show some cousins. Enough of those populations have taken the test to indicate whether someone has black or Native blood, so there wouldn't be a blank slate.
Lastly, if her parents are known, and she's been identified, the family could certainly ask that that information not be shared, but at the same time, EDJD's case would be removed from the missing person's files and we would not see an active missing person's case any longer.