Let's say that the skill was only known to the three fools and they somehow reported it to the king. Now, what do you think a king who'd execute an innocent person without a second thought would do? Kill the dude who can grant you pseudo immortality? Oh hell no! He'd sure as hell silence the three fools, prevent any info leaks, lock this dude somewhere beyond the reach of others, and milk him dry for all he's worth, thus beginning the reign of the legendary immortal emperor. But nope, this shit happens instead.