I was on the Glory at that time, and its true there was a medical emergency. We returned to the dock to await an ambulance from somewhere (I have no idea where the nearest facility was).
The Glory waited for the person involved. He/She received treatment and was returned to the ship. We left Costa Maya about 9:30 local time after a 4.5 hour delay. We were late getting into Nassau, but our departure was delayed so no time was lost at that port. We returned to Florida on time.