alot of my friends from highschool think the same way as your friend does.
I slowly introduced a couple of my sisters to them (usually in the union or something) and wouldn't tell them that they were greek until after my friends said they thought the sisters were really sweet
they slowly started to open up about it. But then again, i still have some friends who just won't accept it. And whenever they say mean stuff, i ask them to stop. and if they don't...i turn on my B**** mode