He was 63 and wrote this a few years ago, “You’ve Had Your Turn –The Case for Euthanizing Everyone at Age 65” https://marshallbrain.com/youve-had-your-turn-the-case-for-e...

His premise seems to be that life past 65 averages out to suffering and a slow decline toward death, which I think many active and happy older people (who don’t wish to be killed!) would argue is very mistaken.

Misanthropic environmentalism isn’t environmentalism at all. Environmentalism designed by humans should be good for humans, not give them scheduled death dates.

That is a very weird and troubling article.

This is likely satire along the lines of https://en.wikipedia.org/wiki/A_Modest_Proposal. The main giveaways are the directness of the language and the time of writing (on the tail of covid when people were unironically making such proposals).