Did you even read the post? It’s an estimate in the context where you have zero information on which to base an accurate estimate. The author’s point is that if you’re making a different estimate you need to actually say what information is informing that.
Human lifespan is obviously not a case where we have zero information, so what is your point in bringing that up?
But often we don't have the information that we wish. Even more often, the information that we have leads us to a story, that severely misleads us. Reminding ourselves of the zero information version of the story, can be an antidote to being mislead that way.
Therefore it is valuable to know how to make the most out of zero information. And if we have information, to think about exactly why it leads to a different conclusion.
"And we have information to think" - then we don't have zero information right?
So, if most processes are in fact like human lifespans, which do not show a Lindy effect, then it is completely wrong to assume that a random process that you encounter will have this property.