Any of you seen lately all the stuff kids try to wear marching down the aisle? Because the school is graduating the student, the school gets to set the rules on what it will and will not allow. We tell our 8th graders they're only allowed to wear what the school provides because we want friends and family to see what they've accomplished, and because some family members don't know when to stop when it comes to this kind of stuff. There's really no reason for kids to be wearing candy or money leis or stoles that boast about their ethnicity.
That being said, the examples in this article go over the line of reasonable in most cases, and that's not okay. As for the feather issue, I wonder if she asked administration first if she could wear it - the article doesn't really say. If she asked but was told not to wear it, that's a different issue, and it's exclusion from this article would make this a pretty crappy job of reporting by the writer.