At a less apologetic level, the math is just bad -- in a way that it is still bad when used by both feminists and traditionalists whenever they speak of women and power. (Sorry, you cannot ask a gender question on the Internet, and expect to escape the MRA point-of-view.)
The observation lacks the notion of distribution. The top end of any distribution with a wider standard deviation is going to lie above the top end of the narrower one, at some point, even if the mean of the thinner one is higher.
So it is ambiguous whether rulership is a relevant measure of the overall power of a group in a society. More generally, it is deceptive to stratify one's observations within social classes.
When they differ, the sexes differ far more in standard deviation than in mean. And it is almost always the women who are clustered closer together.
There are more male geniuses and more male morons. More men are large and strong, but more boys die before reaching adulthood (so they are never large) and more men develop terminal illnesses at younger ages (so they are in other ways less strong). Both ends of most measurable spectrums contain more men, with women "more average, on average" across the board, and surviving women better off on average in those respects where one tail or the other of the distribution involves death.
So it is with the distribution of power. Women may exert more power over other people's behavior, even in societies where men rule. This can be seen in our own society in the ratio of sexes in prison, and the overall trend that the kinds of crimes we punish most harshly are those it is less natural for women to commit, even though the laws are historically written by men, and often explicitly try to favor them.
We look at gender relations from the viewpoint of the working class and those above, by habit, and completely exclude that class that serves primarily as cannon-fodder or beast of burden, never has the benefit of social protections (including marriage), and expects violence as a matter of course. That class simply contains more men.
At the same time, in cultures where parents or leaders approved marriages, women were married upward in class, on average, and entered their husband's social class. If unmarried women retain the class of their birth, and a reasonable fraction of married women enter a higher social class, women can be subordinate in every social stratum, and still better off on average, by being very under-represented in the bottom tier of the society.