Would most of us find it annoying to go to an event, where speakers were supposed to speak on a particular subject, a subject that had been reviewed by the organizers and approved, only to have them speak about something else?
This is really the core point that Marvin, Sam Whiskey and others don't want to understand. Those students weren't attending a religious convention. So, for this Valedictorian to hijack the room to spout his personal religious opinions was rather disrespectful.
I does appear, though, that he had the chutzpa to say what he wanted to share about what makes him tick.
I wonder if Marvin, Sam and other would be so forgiving if this student had spoken about atheism, reinstituting human slavery in the USA, why pedophilia is not so bad, or what he thinks are the virtues of The Holocaust and Naziism? Since his "chutzpa" seems to be the most important consideration, not his subject matter, he should have been allowed to speak about those things with equal protection.