What rock got turned over that brought this topic back to life?

By Benchgod's logic, Mary Corleone didn't exist either, since in the novel Michael & Kay had two sons and no daughters.

And Merle didn't exist either, since in the book Connie married a male secretary to the family less than a year after Carlo's death.

And the deaths of Cuneo and Stracchi must have been figments of someone's imagination, since they weren't killed in the novel.