When I was in academia, it was considered acceptable for one to alternate between his and her when the gender of the subject is unknown. Using his or her every time does sound stilted, but proper grammar often sounds "weird". My highschool English teacher's favorite phrase was "things that 'sound right' are often wrong". That's the beauty of this fucked up language. I refuse to believe that masculine pronouns being the default gender neutral is some conspiracy by the patriarchy, but that's just me.