Well considering we have met all the main girls and that none of them are saying "sorry MC you aren't hardcore enough for me" I don't think any of them are looking for a "bad guy" (like SIN is painted to be). Which one(s) do you think specifically would be more interested in an MC who is part of the group that LITERALLY EVERY SINGLE PERSON has told us to not mess with? The frat MC joins prefers the jocks being "mad" at them then rather even thinking about going after SIN during the prank. With our president saying we made the right choice going after the jocks.Huh...? Why would it need to be doubled to 16? 1 or 2 ROs could be focused on SINs side of things. Kinda like how some of the 8 ROs aren't interested in frats. ROs routes might end up leading to very different places.
We don't know much about SIN. Is the main difference being more extreme with the partying or is there more to it? Are only guys members or is it mixed? Are some of the girls we've met good with SIN? For all we know we know SIN could some form of anarchist's or adventurous group like the gang from the movie Point Break lol.
What we know about SIN is literally everyone both male and female tell us to avoid them. Nobody says to avoid the jocks and they are pretty loudly talking about sending the entire football team after a freshmen just to "cuck" some random guy they just met (the president of the frat says this). Dev has mentioned right now the PED are borderline pantomime levels of comical over the top evil which means that the only way for SIN to step up (from a narrative sense) is that they are more cartoon villians (they will all have twirly mustache) or they are a more "realistic" threat.
Yes frats typically only have males just like sororities only have women (try to think of another example in games/movies/real life), I had to Google it to see if it was even allowed (it has been since the civil war) but couldn't easily find a single report/guess on how many "women join college fraternity" so I assume it's exceedingly rare if done at all.