Yeah, if I understand your point and link: this is not something that actually happened, it's just a joke, but after enough retellings for some reason people think that it is real.
I see the original commenter I replied to said it was just a "tale", but I don't think that's how most readers would interpret that comment. Saying something "happened a few decades ago" is oddly specific if it's just a joke/tale.
Also, the whole point of their comment was to emphasize how foraging for mushrooms is dangerous - using an old wives tale as "evidence" for your position would be a very odd choice indeed.
