You're willing to believe that Avery specifically asked that his character never enter a romantic relationship with a woman who is not brown (Avery's preferred term) but he's totally cool with it if it's only sex?
I'm not saying if it's true or not (I don't know the man or his motivations beyond what he states publicly), only that "someone said it on TrekBBS" isn't much to go on. The imagined idea that he was never with a woman who wasn't brown on DS9 is spurious 'evidence'.
Whom did Sisko have sex with that wasn't "brown"?
MU Jadzia.