At my graduation all us graduands were sitting in the front rows when the grandmother of one of them keeled over in the stands. There was a big commotion, and the paramedics arrived shortly to take her out on a stretcher. The girl sat in the row behind me, tears streaming down her face, not sure what she should do. Finally the attendant came and escorted the girl out. The speeches and the ceremony continued without a break. Near the end, though, they did make an announcement about the lady to tell us she was okay.
I don't think it's necessarily appropriate to stop an event like this and have everyone watch the medical emergency, particularly when it is being dealt with by professionals.
Just a comment on epilepsy seizures. The vast majority of people with epilepsy cope with their seizures without needing an ambulance. As long as they haven't fallen and sustained an injury, all that's required is to monitor the seizure and reassure them once it's over. No ambulance or 911 is necessary. Also, where I live, if you call an ambulance you incur a cost of almost $300 for that individual.