science the crap out of them. gluten sensitivity has really been getting some serious play lately, and people are starting to take it seriously. hit them with studies, news articles, food journals, etc...especially the nutritionist. s/he seems like the best foot in the door.
if that doesn't work, go over them. dining services has a boss, find out who it is, and address the situation with that person. you're not trying to change college policy or anything (though, offering gluten free foods really should be a standard by now on college campuses), you just need them to grant a change to your plan. university brass take a single student's concerns seriously. talk to the dean of students or vp of student affairs if you have to... they are there to advocate for you.