I think you’ve got it wrong. As someone whose father was the director of the Adventist Health Study from 1977 until last year … and who worked as a medical statistician and programmer on that study … I know just a little about this. University, Med School, 4 board certifications … studying like mad for 30+ years post undergraduate. I suspect my perspective might be informed.
You are quite correct … processed vegan or vegetarian stuff … rubbish … and ends up meeting some ethical or religious goal, but if you are purely looking at health … somewhat better than animal based.
The researchers who witness health outcomes vs. lifestyle choices, such as Walter Willett, Christopher Gardner, Valter Longo and my father seem to have a consistent message on dietary pattern - and it doesn’t have to be WFPB - but the closer it gets to that pattern the better the health outcomes - to an extent. Adding limited, high quality animal sourced foods is probably fine … but having a dietary pattern where these foods are usually the majority of intake has nothing but poor outcome data in the long term. There are always individual variances - but Keto done primarily with animal products is not a good longevity plan in general.
However WFPB, or WFPB plus a little fish and a little fermented dairy will, based on decent evidence, rather than idiots pontificating on why they think Keto is best (with no outcome data), demonstrates a decade of increased longevity vs. the standard American diet.
I’m not an ignoramus on the benefits of keto for a very small number of people - but this generally isn’t health outcome based, it is seizures, mental health … sometimes weight (but health outcomes would be better with a better diet and if not able to pull this off with dietary and lifestyle advice, I’ll recommend a GLP-1/GIP … much more sensible if looking at longevity).
Ancestry and history arguments are silly. There was no selection to yield longevity - if your only goal is to get to reproductive age … sure there is selection for that. If you are interested in longevity … just keep pushing that IGF-1 through the roof and promote malignancy, escalate your vascular disease and risk of T2DM with animal protein … that is what a typical keto diet promotes, and will take years off your life.
BTW - I agree with you on the appearance of many of the folks trying to hack their longevity … I think it will end badly for them … they don’t look well. I’m WFPB … and I look well … I’m also not delusional and anticipate life extension with good choices and all my various drugs to possibly be 20 years if I’m lucky.