The people patting the dude on the back and joking about him knowing are gross. Era absolutely has a boy's club problem.
Honestly once you get beyond the shock of the initial read, it really is sad to think that people can be so poorly educated on their bodies.
Since a lot of dudes with apparently no knowledge of female arousal or anatomy are mocking this woman for not knowing, it's entirely plausible to me, as a person with a vagina, that she may not understand where she bleeds from during her period. Period blood often comes out kind of brown or lumpy because it's dead, dried blood. When I first got my period, I legitimately thought shit was leaking out of me because that's how it looked. Granted I got my period before I had any kind of sex ed (I was young for it at 10), but I still was relatively aware of my body and had older siblings who had experienced it already. In a culture where bodies and discussion of these matters is taboo, I'm sure she could have not known where she bleeds from, let alone connected periods with sexual anatomy. Hell, I know plenty of dudes who still think women pee out of their vaginas.
As for arousal hinting her towards the proper hole, if she found (anal) sex unpleasant and painful and was also stressed about perhaps being infertile, I can absolutely believe she may not have been properly aroused.
It's entirely possible that the article is bunk, but I still don't find this unbelievable.