Maybe his thought process was that giving the age twice ("elderly" and then "70" -- do you need both?) would be redundant, so that the redundant number might not be an age.

Indeed. I also consider 70 to be pretty young for a retirement home. Statistically speaking, I assume the vast majority of 70 year olds (95+%) are living independently. So I thought either OP is being redundant and low-balling or giving a sample size. Didn't know.

Btw, through a quick web-search, it appears the average for new residents is mid-80s.