Nobody would even think to complain if the implication behind this post was that the company was self-sabotaging itself.

To briefly speak of ethical and legal issues, it is highly doubtful that they would have a policy of not hiring women if women actually apply for the position (and that would most certainly be illegal). Much more likely is that whoever ran the Facebook campaign checked off that option in an dumb attempt at controlling ad campaign costs? Or maybe they ran a separate campaign to recruit women? Or maybe some other non-nefarious reason.