"That would seem to be something of an outlier, its tough to say that it aged him, he just appeared rather sick on it and such effects have rarely been reported."
.....
"if I took stearic acid regularly for months, wouldn't the stem cell pool just keep growing and the body slowly adapt to this bounty of stem cells and regenerate, just more slowly?"
I agree with your first statement that that individual simply appeared sick on C60. We don't know much about him, but he seemed to be affected too quickly for his side effects to have been caused by stem cell depletion. In his case, I think its more likely that he was ingesting either poorly made C60, or C60 that was old or left out in sunlight. He was also consuming other exotic substances such as NSI-189, so who knows if his effects were even caused by C60 at all.
Regarding your second statement, as Turnbuckle stated, stearic acid alone is insufficient. You first need stearic acid (to induce fusion) and then c60 (to block the ucp pores on the mitochondria of stem cells). See the quote below that I took from one of Turnbuckle's earlier posts, which he took from a scientific paper.
"Here, we show that hPSCs [human pluripotent stem cells] have functional respiratory complexes that are able to consume O(2) at maximal capacity. Despite this, ATP generation in hPSCs is mainly by glycolysis and ATP is consumed by the F(1)F(0) ATP synthase to partially maintain hPSC mitochondrial membrane potential and cell viability. Uncoupling protein 2 (UCP2) plays a regulating role in hPSC energy metabolism by preventing mitochondrial glucose oxidation and facilitating glycolysis via a substrate shunting mechanism. With early differentiation, hPSC proliferation slows, energy metabolism decreases, and UCP2 is repressed, resulting in decreased glycolysis and maintained or increased mitochondrial glucose oxidation. Ectopic UCP2 expression perturbs this metabolic transition and impairs hPSC differentiation. Overall, hPSCs contain active mitochondria and require UCP2 repression for full differentiation potential."
https://www.ncbi.nlm...pubmed/22085932