That omission today seems unfathomably cruel and - that gravest of sins - hypocritical. While Thurmond was running for president of the United States as a Dixiecrat segregationist, his own flesh and blood wasn't allowed to vote and he was fighting to keep things that way.
Yet he kept Washington-Williams in his life.
Say what you will about what might have been, what Thurmond should have done, how the South might have been different had Thurmond been straight-up about his interracial relationships, he was no deadbeat. He supported his daughter, sent her to college and was financially reliable throughout her life, Washington-Williams said.
Cynics and critics may prefer to say he paid off his child to keep her quiet, but Washington-Williams' grace and history belie the charge. If profit were her interest, she could have gotten millions for this story while Thurmond was living. Moreover, she isn't seeking money now, though a book and movie seem probable.
By her own explanation, Washington-Williams and Thurmond respected each other. "I never wanted to do anything to harm him or cause detriment to his life or the lives of those around him," she said during her news conference.
He was, after all, her father.
There are as many jokes about Strom Thurmond's legendary libido, his womanizing and his stubborn longevity, as there are stories about his generous constituent care, evenly distributed among blacks and whites, and his metamorphosis from staunch segregationist to inclusive benefactor.
All contribute to the justifiable wonder with which others view Thurmond's home state and lend credibility to the possibility that South Carolinians are indeed insane. If Strom Thurmond rose from the dead today - and some reckon he might - voters probably would re-elect him to the Senate, sponsor a reunion for his biracial family, and politely avert their eyes from the unpleasantness of his hypocrisy.
Things happen in life and, goodness knows, life is complicated.