I think both sides have a point. Back in the early 80s, in high school, we were talking about graduation and baccalaureate. (not my class, the one before it, I think). They were going to have a priest or something. Two young ladies, who were graduating, said at lunch one day "If they get to have a priest, I want to bring in my Rabbi". I thought that had a point (I wasn't even a theist then) and I thought, "why can't they bring in some other religious leaders, as well as a priest?" My view of the "if everyone can't have theirs, there will be none" might be a bit extreme. Of course, there would have to be some kind of limit or prayers would go on for too long (I mean on the length of prayers). But it is something that the people graduating need to discuss.