In Requiem for Methuselah, it is stated that Flint lived in solitude on his planet to escape the 'unpleasantness of life on Earth'.
McCoy discovered in the end that Flint had sacrificed his immortality by leaving Earth, and would live the remainder of a normal life.
A couple of questions. Uhura revealed that the planet hads been purchased by a "Mr. Brack" thirty years earlier. Was this individual supposed to be Flint? If so, he'd been on the planet for thirty years. You would think he'd have noticed himself aging in that time. Ironically, his venture to create the perfect, immortal-like-himself woman was futile, since he was now to age and die like everyone else. That's pretty sad, actually.
Also, did our heroes ever question just how this one human from the distant past gained this ability? Did they ever ponder whether there were any more like him around? How just this one man out of all human history being blessed with immortality is pretty odd...
McCoy discovered in the end that Flint had sacrificed his immortality by leaving Earth, and would live the remainder of a normal life.
A couple of questions. Uhura revealed that the planet hads been purchased by a "Mr. Brack" thirty years earlier. Was this individual supposed to be Flint? If so, he'd been on the planet for thirty years. You would think he'd have noticed himself aging in that time. Ironically, his venture to create the perfect, immortal-like-himself woman was futile, since he was now to age and die like everyone else. That's pretty sad, actually.

Also, did our heroes ever question just how this one human from the distant past gained this ability? Did they ever ponder whether there were any more like him around? How just this one man out of all human history being blessed with immortality is pretty odd...