I've got to be on the side of the "establishment" in this case. Every graduation ceremony, including my own, that I have ever been to, they have asked the parents/grandparents/friends/etc. to refrain from cheering/clapping/etc. until after the entire ceremony is over. This is pretty standard fare.
Also, at every one of those that I have attended, including my own, some parents/friends/etc. obviously felt that they were excluded from this and chose to cheer/hoot/holler/etc. when their child's name was called. This usually resulted in a reminder by the MC to not do this.
I personally don't think you're asking a lot of people to sit and behave like adults while the ceremony goes on. Again, at all of the ones that I have attended, there is a time for cheering/clapping/hooting/hollering/etc.
I think the folks that choose to ignore that are rude and inconsiderate to others. I've got no problems with the perpetrator being arrested or at minimum escorted from the venue. Denying diplomas is also fine by me. After all, they're not asking people to perform brain surgery - just behave.
The other part of me also says if you don't like the rule, then don't go the graduation ceremony. You'll still be graduated, still get your dipoloma, the ceremony is just that - a ceremony. If you want a raucous reaction when your name is called, gather all your supporters in a room of your house, have somebody call your name, and everybody can cheer. Problem solved.
I applaud that the woman was removed for doing what she was told not to do, in the manner in which she was warned she would be removed. I've read some other stories regarding this matter, and so far, all of the students and parents that are being punished are being punished in the manner in which they were told they would be punished for the infractions they committed. I can't see anything wrong with this. Again, if you don't agree with the rules of the ceremony, and can't behave as prescribed, don't go.
Or go ahead and get on the plane and start talking about blowing it up, don't sit down and latch up your tray table, and other disorderly conduct, and then see what happens.
Just my opinion. I think these people got what they deserved.
Good luck and take care.