Just going by the abstract that you linked, that study seems to only relate to the past 100 years.

And extrapolating this to the middle ages and earlier:

In general, countries with a lower overall life expectancy had a lower number of women per 100 men aged 75+, while countries with higher overall life expectancy had a higher female to male ratio in this age group. A hundred years ago there were nearly equal numbers of women and men aged 75+ in many countries.

It doesn't seem to disagree with me at all.