someone of his type said basically that longevity can be an incredibly incisive social issue, because initially it will be expensive, and if rich people can live to 200 and poor people die at 70 this can easily lead to the pitchforks

The most recent place I heard this was Death is Optional, and it was said by Yuval Noah Harari:

HARARI: Death is optional. And if you think about it from the viewpoint of the poor, it looks terrible, because throughout history, death was the great equalizer. The big consolation of the poor throughout history was that okay, these rich people, they have it good, but they're going to die just like me. But think about the world, say, in 50 years, 100 years, where the poor people continue to die, but the rich people, in addition to all the other things they get, also get an exemption from death. That's going to bring a lot of anger.

But it was also in the context of pointing out that we're used to mass power and successful revolts--but it could very well be the case that an anti-longevity revolt gets put down by robot police.

HARARI: Once you are superfluous, you don't have power. Again, we are used to the age of the masses, of the 19th and 20th century, where you saw all these successful massive uprisings, revolutions, revolts, so we are used to thinking about the masses as powerful, but this is basically a 19th century and 20th century phenomenon.

If you go back in most periods in history, say to the middle ages, you do see peasant uprisings. They all failed, because the masses were not powerful. And once you become superfluous, militarily and economically, you can still cause trouble, of course, but you don't have the power to really change things.

Once you have the revolution we are undergoing in the military in which the number of soldiers simply becomes irrelevant in comparison with factors like technology, you still need people, but you don't need the millions of soldiers, each with a rifle. You need much smaller numbers of experts, who know how to produce and how to use the new technologies. Against such military powers, the masses, even if they somehow organize themselves, don't stand much of a chance. We are not in Russia of 1917, or in 19th century Europe.