In a specific case, certainly. In the general case, subconscious bias plays a role. It doesn’t seem like a real argument that, generally speaking it is unknown

In a specific case, certainly. In the general case, subconscious bias plays a role. It doesn’t seem like a real argument that, generally speaking it is unknown whether race or gender bias is more of a determinant in hiring decisions than hair color bias. Is that an argument you consider rational? HR policies do have measurable outcomes. It's a question of what you think those measurements describe. A diversity hiring HR policy is a counter-action to the existing subconscious bias favoring white men, and a long term effort to squelch subconscious bias favoring white men by increasing exposure to diverse races/genders. Let's collect some long term data and analyze the result measurements, instead of pretending subconscious bias favoring white men doesn't exist.