https://en.wikipedia.org/wiki/Survivorship_bias
what about all the people who challenged what was "considered normal socially" and actually were proven wrong? One never hears about those.
Maybe if you'd added, "of course, lots of people who wound up dying in a mental asylum are forgotten, with good reason" then I would've had nothing to say.
As it was, you cited an example as though that proved anything.
There are not many of those, because of herd mentality. (Edit: I mean Normalcy Bias, thanks "notabee")
If a person is unusual enough, they are dismissed as cranks without any sort of proof required.
notabee held up one example, which is relevant only if the argument was "everyone who challenges the norms is insane." That would be a counterexample, and only one is required.
as for "There are not many of those" I don't even know what to say. Of course those people were forgotten and there are no citations, because they weren't newsworthy. That was the whole point.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240806
What's considered normal socially is not always what's supported by the evidence at hand, and sometimes what that supports is well outside of the acceptable range of discussion or behavior at the time.
Are you truly concerned that this person has made an error in judgment based on evidence or do they just make you uncomfortable for breaking norms? Are you motivated to post about this because you've considered their reasons and think they've made a harmful, critical error in judgment or are you just seeking approval of your normalcy bias? Do you know enough about their health situation or their family's to be sure that their risk calculation is unreasonable?
The best course of action if you're absolutely sure that there's no threat to you is to ignore them and move on with your life.