I believe this is a very weird ponderation. The whole point is that capitalists don't do that because there is sexism among them. They are ignoring rational evidence because they have a preconceived idea that women are worse employees. If capitalists were actually these rational straw man devoided of human flaws, we wouldn't have sexism at all.
So this line of thinking is basically saying: if there wasnt sexism we wouldn't have sexism.
A more practical way of making my point. In past decades black athletes werent admitted in competitive sports teams. Would you say that you believe that wasnt racism because if it was, team owners would be tripping themselves to hire talented black athletes that were being ignored by most teams? No, they werent because they were racists. It took a lot of civil right activism to give black athletes the same access to sports jobs as white athletes. And today we know for a fact that black athletes werent worse athletes back then.
Why are today employers more enlightened that past team owners?