Unlike other events, where strength is a limiting factor (for instance, sprint speed is limited by muscle mass), there isn't much of a reason to believe that women would be worse at distance running.
For instance, the same line of logic would be 100% chauvinistic if someone said "The best engineer in this field is a woman, but it's a narrow field, I assume the sample size is very small."
People used to make very similar claims about the inferior mental capacity of women as they do about physical performance now. Yes, men outperform women in feats of strength, however, in many sporting disciplines the fact that men continue to outperform women is most likely due to the fact that men are generally encouraged to participate in sport to a greater degree than women, and sporting communities are more welcoming to men.
The author of the comment I replied to has no basis for his claim that the sample size accounts for the women winning beyond a feeling that men are superior athletes in all ways. That is chauvinism, and if that claim makes you feel uncomfortable or angry, perhaps you should reflect on why that is.