I'm completely confused. I rather enjoying making friends with people at work, male or female (and regardless of "rank"). If you've met someone before, and people are "milling about in an open space", why on earth wouldn't you give each other a warm friendly hi? Why is he suddenly "a fool" in a situation that is "not good at all"? And assuming he's still feeling "all warm fuzzy" (what does that even mean?) As a man, I almost feel insulted by all the assumptions being made here, and the idea that my own natural socialness might one day be so misinterpreted.
Maybe something's missing from the story, but I can't even begin to comprehend a place where a friendly hi between two people who met and chatted in a stairwell, or elevator, or lunch line, or any of the other 100's of places you run into coworkers at all levels, is somehow a bad thing. I mean, if the dude's some kind of a creep, then I get it, but the author says he's a nice guy.
Total confusion.