Unfortunately, this article doesn't give even the slightest hint of what she started to say, much less what she was planning to say. If she was starting a rant exhorting the audience to adopt her religious beliefs, that would have been inappropriate. On the other hand, just sharing what her own beliefs are shouldn't be a problem, unless school officials are going to prohibit any topics that could possibly offend a significant number of listeners. Somehow when graduates give leftist political rants, they don't seem to get their microphones cut off. While I don't share this young lady's religious beliefs, if I were in the audience, I'd a lot rather listen to her to explain her religious beliefs and how she thinks they helped her do well in school, than to hear a student carry on about how "we need to get guns off the street because they're killing children" or "war is never the answer" -- and I don't think the ACLU or anyone else would cut off the mike for the latter.
But not illegal.
She can say whatever the H-E-double toothpicks she wants as long as it isn't immoral nor obscene! She's the valedictorian. She earned her place at the rostrum. Because she was going to share her faith, she was silenced. That is wrong in these United States!
How long until students are handed their speeches by school administrators and told what they will say?
So are the scores of people who booed the fact that her speech was cut short willing to step up and start standing up to the ACLU?