The concrete claim by the parent is "nearly all of the racist scenarios were fabricated out of whole cloth." It's not a "discussion of what really happened," it's a flat-out attempt to minimize well-documented racist behavior and systems. This is as if someone watching a Ken Burns documentary complained the narrators were not the true primary source authors.
Agreed that "fabricated out of the whole cloth" is an exaggeration. Rather than go into it further, I think it's better to encourage people to read history and learn stuff than it is to get into the usual culture war about this.
