The website you mentioned didn't outright saying it cannot happen. They just said it was not the reason every time.

But never says it will never happen, maintaining it's speculative.

They try to not give definite statement there. And even if it does, it won't happen in all cases... Avoiding saying "it will never happen", instead goes for maybe sometimes, but not all the time.

I'm focusing on them trying to make sure they don't give a 100% verdict, leaving room for later in case it turns out to be true.

The most likely source of male Mc in female brain is acquisition of fetal Mc from pregnancy with a male fetus. In women without sons, male DNA can also be acquired from an abortion or a miscarriage [22], [23], [38]–[40]. The pregnancy history was unknown for all but a few subjects in the current studies, thus male Mc in female brain could not be evaluated according to specific prior pregnancy history. In addition to prior pregnancies, male Mc could be acquired by a female from a recognized or vanished male twin [41]–[43], an older male sibling, or through non-irradiated blood transfusion [44].