Immortal tyrants would rule forever - it would be like "Brave New World."
It is undoubtedly true that authoritarianism poses a serious problem for our society. However, relying on cardiovascular disease or cancer as the main strategy for regime change is both ineffective and ethically catastrophic. In any case, dictator ranks pretty high on the list of the most dangerous professions: throughout history, tyrants have been overthrown, sent into exile or assassinated far more often than they have died of old age. Removing aging from the equation does not make a dictator invulnerable.
Moreover, even when aging kills a tyrant, it rarely kills the tyranny. Autocrats have decades to groom an heir or name a successor, and most dictatorships outlast the dictator.
The most important factor, however, is the sheer scale of the collateral damage. Accepting aging just because we fear a few immortal tyrants means actively accepting the suffering and death of countless innocent people. Had Pasteur not laid the foundation for modern vaccines, some of the worst dictators of the 20th century might never have reached adulthood. Yet no one would seriously call for a return to a world in which almost half of all children died of preventable infections before their fifteenth birthday. Condemning billions of people to an agonizing death just to ensure that a handful of autocrats meet the same fate is a completely untenable trade-off from a moral point of view.
We must tackle political problems with political solutions, and medical problems with medicine.
External links on the topic of "immortal dictators"
Lifespan Extension Advocacy Foundation: Immortal dictators? | LifeXtenShow