While this might be a bit wide of the point of this thread, these are my thoughts on the the overall issue of gender, role-playing, and search threads.
It's a common stigma that only men are super fans of things that are traditionally considered "nerdy". So, when we see someone with Star Wars, Star Trek, DnD, or some hardcore game in their avatar and signature; we are more or less conditioned by society to believe that they are male. Despite what statistics show us, most people will not encounter many women who are fans of traditionally male fandom. I rarely encounter a woman that has ANY interest in the original Mobile Suit Gundam. In fact, I can't recall ever running into one. Despite my personal experience, I know that there ARE women out there that enjoy it. Most people are unable to separate their personal experiences from the larger picture: just because we experience something, it doesn't mean it's truth. We rely on our intuition to tell us what occurs most often, and then act on it.
Our intuition will tell us that it is absolutely safe to go outside in most conditions. We have no reason to doubt this, because we can go outside, numerous times, every day, all year long, and nothing bad will happen to us. In this case our intuition is entirely correct, and is guiding us to do something relatively healthy and often necessary for survival. However, at the same time, if all we know are male Star Wars fans, our intuition will tell us that most Star Wars fans are male. Our experiences shape a picture in our mind that our brain will then peek at without us even knowing it. We rely on our intuition so much that we will sometimes blindly follow, and completely ignore the fact that we cannot possibly draw an accurate conclusion.
A person's complete trust in their own mind and intuition will lead them to believe that a ghost has done something in their house, despite having no good reason to think so. They trust that, because they cannot rationally think of any other cause, that the supernatural must be the answer. Their intuition, programmed by popular media and the tall-tales of others, tells us that it was a Ghost. Without even thinking some people will immediately attribute any odd occurrence to some supernatural means. So, is it so hard to think that people will assume that 501st is a man? Maybe 501st is, but that's nothing but a lucky guess founded on nothing but perceived (likely incorrectly) probability.
That being said, my threads tend to get very very few hits. I mostly role-play fandoms, and often the ones that aren't as commonly listed in the Female Requests. If I were to put my threads in the Female Requests, I suspect I would have more luck. What we have to realize is that the Internet is largely anonymous. We don't have any sure way of knowing if the people behind any one of these accounts is actually male or female. I can put any gender I please in my profile, or none at all. That female request made by the self-proclaimed lesbian, seeking hot pussy and no boys, might just be a man. That guy looking for a well-written, lengthy, role-play might just be a woman. The "guy" with the storm trooper avatar and signature could be a woman. The woman looking for an abusive man to teach her the ropes might be a man.
Bluemoon is a website that asks very little of it's users: you follow the rules, and don't be an asshat. This is the place where you have the freedom to write almost anything you want and completely embrace the anonymity that the Internet affords you. There is no interview process, no gate to climb, and no asses to kiss. You join, you post, and you be a good boy or girl or whatever. We have to understand that that freedom will be exploited. There is no way to accurately determine, to gather statistics, on preferences of role-play via gender. The ten guys you just role-played with may have been a mix of both male and female and whatever else. The very topic of this thread is entirely flawed, because you don't know who you are actually role-playing with. It would be more accurate to ask: Which category of request thread gets you the most hits?
The categories are entirely arbitrary, from a standpoint of gender, and matter very little on BMR. As the descriptions read, it's more about whatever persona the person wishes to write as.