As with a lot of tropes, we're having trouble nailing down terms, too. As you allude, we've at least meant a few different things by "conservative;" 1) social conservatism, 2) technological nostalgia, and 3) scientific conservatism. This seems to be one of those memes (I use the word deliberately as a "persistent mental structure or coding," separate from the term "idea.") that survives by coding multiple actual ideas. Not that you're doing the following, but reciters of the meme can always switch between ideas/fields when the current case becomes problematic. Societies don't become conservative? Well, what about Kuhn/Planck and scientific conservatism? Oh, scientists do actually adopt new theories late in their careers? What about people who restore classic cars? People buy new cars late in life? Well, societies become more socially conservative as the population ages. And so on.
One final point that, again, you're not doing right now, but I find ironic and amusing. Critics of life extension will oft lament that "mortality makes us human," and that we'll become inhuman monsters if we routinely live to be 1000. Then, in the next breath, they'll then insist that we'll behave exactly as if we died at 80 when it comes to things like conservatism, or reproduction, or career choices. But that's just the amusing part; the ironic part is that they'll do this at just about any age!
> Nearly a third of Boomers (31%) and 36% of Silents described themselves as conservative Republicans or Republican leaners, which also is higher than in the past.
http://www.pewresearch.org/fact-tank/2017/03/20/a-wider-part...
It's not a disinclination to starting over that fuels (social) conservatism, but rather a yearning for an older, simpler, "more virtuous" time (one often that never actually existed, except in the imagination).
This is how you wind up with old people wearing clothes that were fashionable in their youth, still behaving in "old fashioned" ways, still consuming media from bygone eras, etc. Not that such behaviors and tastes necessarily make you a conservative, nor is this restricted to just old people. Some young people also yearn for the past, and enjoy affecting styles of dress and consuming media from bygone eras. But the cause of such sentiments is shared with conservatives: that is, it's a rejection of modernity and a yearning for a mythical past.
People who are "living in the past", as it were, or wanting to re-create the past in the present aren't interested in reinventing themselves or embracing the present or the future. If anything, living for longer is likely to exacerbate this. The feeling of nostalgia and yearning for an older time is likely to get worse, and the inability to cope with the modernity is only likely to increase (barring breakthroughs in psychology, sociology, neurology, or psychopharmacology that might make such coping with and accepting of the chaotic and ever-accelerating present/future easier).