It's a bad analogy, and not well thought out, apparently. I think that it was the idea that it seems like Danny is always trying to get Steve to express emotions other than anger (and its family) and Steve seems to want Danny to be a bit more stoic (like him). Chin takes on the big brother role a lot of the time (obvious reasons are obvious). It seems like, of the main cast, Kono gets to display the biggest range of emotions, perhaps because she gets put into the most different situations?

That's what it appeared like to me. But I may not be right. So "emotionless men" was more "single-emotion men", I guess. And that's still probably wrong.