The problem the parent post is pointing at is that personalities differ among different groups of people. So that guy who may seem a bit taciturn and therefore

The problem the parent post is pointing at is that personalities differ among different groups of people. So that guy who may seem a bit taciturn and therefore, "not a good cultural fit" may actually be a great employee, it's just that in his cultural group it's not normal to be super bubbly and talkative when you first meet someone. It's not about quotas or diversity for diversity's sake. It's about recognizing that we all bring our own cultural lens to a situation and not being aware of how that influences your perception can lead to judging great people more negatively because they're not like you. The challenge is that one has to be self-aware enough to recognize their own biases and still make some value judgments on personality.