I think the fact this study used undergrads should disqualify it from being taken seriously. I'm a guy in my thirties and I've managed to cultivate adult friendships with women without wanting to bone them, and vice versa.
That being said, there was one girl a few years ago who was one of my closest friends for several years. I thought she was about the coolest person I knew, but she was in a serious relationship the first five years I knew her, and by the time she was single I was of the opinion that we would not make a very good couple - we were a little too much alike personality-wise, and we were not really each other's type. It would have been like wanting to date my sister-in-law.
Then a couple of years went by and we got to be so close (the talk-every-day-no-matter-who-else-we-were-with type of close) that I fell in love with her. She wanted no part of a relationship with me, wouldn't even consider it. It wrecked our friendship completely. Broke my heart. Another four years go by, and this summer we were back in touch again, and she told me she had just gotten re-married (first hubby was the five-year relationship she was in when I first knew her). And though it had been a few years, this came about at a bad time in my life and so broke my heart all over again.
We tried to reconcile as friends anyway and couldn't do it. She told me just trading emails about what happened a few years ago brought back some of the same guilt and anxiety she felt when we first went our separate ways. Even after all this time, she couldn't even acknowledge what had happened.
Moral of the story: men and women can be friends. But when they can't, it can punch you in the crotch as hard as any break-up.