I have to credit Mrs. Veil for finding that. When the whole Liz Cheney thing was going on, I guess she got curious and asked Siri if Dick Cheney was still alive. I came home from work and my wife wanted to know why Siri wouldn't answer that question.
I tried searching Google for other examples of this, but even including Siri in the search phrase "Siri is Dick Cheney still alive", I come up with nothing. So as far as I'm concerned, Mrs. Veil is officially the one who discovered this strange quirk.