The mean height for men at 20-29 is 69.2" and 80+ is 67.1" (measured in 2015-2018, the last data I've found) [1], which could be interpreted as shorter people having lower risk of all mortality. One could say that people are just getting taller over time and 80+ y.o. were shorter at their 20-29, but we also have the median height for 20-29 fro 1970s, when 2018's 80+ were 20-29 - it's actually 69.7" [2], men in the US are getting shorter over time, so unless people naturally shrink 2" with age the data points to shorter people having lower risk of death.
1. https://www.cdc.gov/nchs/data/series/sr_03/sr03-046-508.pdf
Short people have fewer incidences of cancer, so I don’t think you can say that lower overall risk of death implies lower risk of heart disease.
As for 2, men in the US are getting shorter because of immigration which adds many confounders.
I am not saying that. I am saying that the theory about absolute amount of fat being bad for health, as stated by the comment you responded, seems to be supported by data.
People do tend to shrink in height quite a bit at advanced age.
https://medlineplus.gov/ency/article/003998.htm
"People typically lose almost one-half inch (about 1 centimeter) every 10 years after age 40. Height loss is even more rapid after age 70. You may lose a total of 1 to 3 inches (2.5 to 7.5 centimeters) in height as you age."
So people DO in fact tend to lose about 2 inches at age 80 versus their younger selves.