This has been my go-to "that can't possibly be right" factoid for years. He had two living grandsons the last time someone made me Google it. It looks like one of them indeed passed away in 2020, but the other is still alive albeit no longer in good health[1].

I can never remember when John Tyler was President but he was born in 1790, 232 years ago, which makes it sound even more implausible. We are further in history from the Ice Bucket Challenge than this still-living guy's grandfather's birth was from the end of the American Revolutionary War.

[1]: https://en.wikipedia.org/wiki/Harrison_Ruffin_Tyler