The Principle of Charity would suggest that the grandparent comment was not trying to control for age differences, but was sharing an anecdote that many folks in the grandparent’s neighborhood were of similar age, leading to a hypothesis, and draw what conclusions you will.
I interpreted that to mean, walk more floors, get more exercise, live longer, which aligns with conventional scientific wisdom.
That's an interesting principle* and I totally get it, but I'm not 100% sure it applies here?
This is a comment section on an article about scientific data quality, and I'm pointing out a potentially confounding issue with the anecdata? Another valid challenge would be "wouldn't people with more health issues choose to live on lower floors, and logically be expected to pass away sooner?"
It's possible I've been reading too many Data Colada posts, but I saw the OP got back to me with a plausible explanation that enriched my worldview, so I'm going to take it that the OP didn't find offense in my response.
* One immediate problem I see with that principle is that it can quickly become circular. For example, an easy criticism of anybody attempting to reference it, as you did here, is to ask: did you apply the principle to my comment? And in turn, you could say the same of mine!
I interpreted that to mean, walk more floors, get more exercise, live longer, which aligns with conventional scientific wisdom.