My grandfather never took supplements and died at 96 from pneumonia. Genetics?
Who knows? And what caused Linus Pauling's prostate cancer in his 90s?
No one has all the answers concerning what is beneficial or detrimental in the areas of health and nutrition. It will be many more decades before such questions are answered.
And anyone claiming to have definitive answers about much of anything should be viewed with great skepticism. Studies such as this prove nothing. The occurences of kidney stones are very small both among the groups using or not using vitamin C. And there are many other dietary factors that could have affected the outcome.
People just have to use their own judgment and instinct because these debates have many more decades to run.