I think in a large part, it depends very much on the individual community of each school. I went to a Quaker boarding school in the 90s and experienced vastly less sexism than was in my previous public school. (posted to Boarding School: As Chauvinist As Ever?)
This is pretty weird, I agree, I'm surprised it was allowed and it is a sign of an extreme masculine culture. That's too bad. On the other hand, at my college females hold 70% of leadership positions and their average (posted to Boarding School: As Chauvinist As Ever?)