responsibility
I'm no expert, but the key here is the reckless operation of the powerboat. Even if the sailboat was displaying the minimum required lighting (and some experts have determined the lights were on), it would be difficult for a powerboat, operating at a speed fast enough to have caused that damage, to see the sailboat in time to avoid collision, especially with lights on shore behind the sailboat. So the state of the lights of the sailboat should be a moot issue.
While the sailboat operator had been drinking and was possibly legally intoxicated (not clear in the BoatUS article), his intoxication wasn't the cause of the accident. There was no action or lack of action on his part that caused it to happen.
The issue of lighting does raise an interesting question, though. If you hand the helm over to someone else, do they instantly become legally responsible for all aspects of operating the vessel, such as lighting, signaling, number of life jackets, charge on the fire extinguishers, etc? The guy being charged is not the owner of the sailboat, he just happened to be at the helm at the time of the accident.