Your sample isn't really large enough to draw any firm conclusions but here are some thoughts on male/female teachers.
To teach salsa you have to be able to lead. Many excellent and experienced female dancers have no interest in leading, they are happy to express themselves and are fulfilled as followers. A man with plenty of experience leading can easily dance the followers steps. In fact, I think to be a top class leader you have to be able to follow too. It's a shorter step from there to become a teacher.
Often, the man and woman teaching are a genuine team but because the leader's role requires more explanation the man will talk more than the woman, so it might appear that he is the star of the show.