Apologies for the late reply.

The original disagreement was you saying "The concept of retirement is ... fairly new" and me disagreeing. I still think that sentence is plainly false for most sane values of "retirement".

The concept of retirement isn't new. But the phenomenon of mass and/or purely age-based retirement is new. My original comment may have been unclear about this. I never intended to imply that the concept itself was new and retirement completely unheard-of; but it was until recently very rare and not a significant driver of social change. There wasn't much point in talking about "retirees" as a group with particular needs or behaviors.

Only kinda because first, as your Wiki link shows, that idea in its contemporary form appeared more than a hundred years ago;

I'm counting that as "new". (Also, in most of the world, it appeared much later, almost within living memory.) My original point in mentioning retirement was that it's not a universal, common, or necessary feature of human societies, it might plausibly disappear again in the next century, and so it might be a bad model for deathist attitudes.

and second, because retiring after a term of service is an ancient custom, going back to the Romans (as usual :-D).

I thought Roman soldier retirement was more a change of career: they took up farming and settlement instead. But maybe they did so with a nice pension that let slaves do all the work. So I concede that yes, this is a good example of widely practiced retirement, and there may well be others. The introduction of retirement in the 19th century wasn't a unique invention. But I don't think this detracts from my original point, that such retirement is uncommon and likely to disappear again in the future.

Going back to the question of why contemporary retirees are... problematic, let me suggest what I think is a standard explanation -- the main cause is the breakdown of the extended family and the alienating character of cities.

I don't think this and the following passages contradict what I said. People didn't retire in the sense of not doing anything productive; they just did other things, and maybe less of them, as they became less capable over the years. Modern retirement is a new phenomenon.

Both the Luddites and you say that automation causes unemployment and that is empirically not true.

I disagree.

Automation causes, almost tautologically, job loss. Whether there are enough other jobs, pre-existing or created, to avoid unemployment is a separate question. Until today there automation has been insufficient to cause high unemployment. I believe that in the next 50 years there is likely to come an inflection point after so many jobs will be automated away, so quickly, that the market will not be able to keep up (even if in a much longer term more jobs might be created again), and societies will have to choose some non-market answers to letting people live without earning money.