Corder's Rights Not Violated

Huffington Post: When Erica Corder gave her commencement speech at graduation three years ago in Colorado, Lewis-Palmer High School was not expecting an endorsement for the Christian faith, but Corder decided to include it in her speech. Following the speech, the principal asked her to write a letter stating the views were Corder's own. Without writing this letter, she was unable to receive her diploma. Corder sued the high school, but the Supreme Court did not hear the case. Why? The school wasn't violating the First Amendment since she was at a school-sponsored event.