Commencement is a time of celebration and accomplishment. The students are well aware of the existence of the problem; that's the exact reason they're booing.

It's like going into your therapist's office and having them trauma-dump on you. Their issues might be entirely legitimate; it's still not the time or place.

For comparison, see Mr. Rogers: https://www.youtube.com/watch?v=907yEkALaAY