We had a couple sisters who rarely drank, one because she just didn't like the taste and one cause she was a townie and didn't want to go home to mom & dad all buzzed.
My (and most sisters') basic outlook was "fine, whatever, more for me!
" They were 2 of the most fun sisters to be around and it wasn't like they "preached" to anyone, so I didn't give a crap if they drank or not. By the time you get to college, the peer pressure to drink like it was in high school is pretty much gone - people are growing up and they don't need someone to validate their choices. Your friend should be fine.