That's a good data point. Although many people program for both OSs, it at least raises the question of why make a Windows app, if it's not your preferred platform?
Let's say it was Sassaman and that it's true that he was primarily a Unix programmer. If he didn't have any pretenses that it would become an immediate hit, he might have focused on coding in his comfort zone. Presumably the people he interacted with who were most interested were probably also Unix users.
On the other hand, he was Bram Cohen's roommate, and he saw BitTorrent take off as a mainstream product. So it's quite possible he was sensitive to the idea that a Windows program would have more viral ability to pick up users.
In any case, he probably would have assumed that if the system gained even a minimal level of adoption, it would quickly be ported to all platforms.
