The goal of this study, AFAICT, is to prove Summers wrong in the name of PC. The fact that they mention the Summers controversy in the first paragraph kind of gives that away. Summers was talking about why 'women may have been underrepresented "in tenured positions in science and engineering at top universities and research institutions"'.
It's telling that the authors of this study chose to include data from 86 countries in order to prove their point. In fact, they choose to focus on countries like Tunisia and Bahrain to make their point. Why not the USA, where most of the people in the tenured positions are coming from? Because when they do, the best that they can come up with is a statement like this: "For example, Hyde and collaborators ([20], [25]) reported that girls have now reached parity with boys in mean mathematics performance in the United States, even in high school, where a significant gap in mean performance existed in the 1970s. Likewise, both Brody and Mills ([3]) and Wai et al. ([51]) noted a drop in nonrandom samples of students under thirteen years of age, from 13:1 in the 1970s down to approximately 3:1 by the 1990s in the ratio of U.S. boys to girls scoring above 700 on the quantitative section of the college-entrance SAT examination."
3 to 1 is still huge, and they are trying to make the case that this result might keep going until it is 1:1 like the mean result already nearly is. In fact, that the result of boys:girls in SAT score above 700 (a measure of variance) is still 3 to 1 while there is gender equality in the mean result is an indication that probably 3 to 1 is the most female favorable result that they are going to get. Because the SAT is a proxy IQ test, this is basically saying that while the mean is equal there are 3 times as many men as women in the IQ stratum from which the people who are gifted enough to enter tenured positions in science and engineering at top universities and research institutions can be drawn from.
But let's ignore that and focus on Tunisia and Bahrain, shall we?