Responsible for what?? Responsibility for the accident lies solely with the captain of the boat the way I see it, and the way I read the law.
Here is the law.
The size of divers-down flags displayed on vessels must be at least 20 inches by 24 inches, and a stiffener is required to keep the flag unfurled. Dive flags carried on floats must be at least 12 inches by 12 inches. Also, divers-down flags on vessels must be displayed above the vessel's highest point so that the flag's visibility is not obstructed in any direction.
Divers must make reasonable efforts to stay within 300 feet of a divers-down flag on open waters (all waterways other than rivers, inlets, or navigation channels) and within 100 feet of a flag within rivers, inlets, or navigation channels.
Vessel operators must make a reasonable effort to maintain a distance of at least 300 feet from divers-down flags on open waters and at least 100 feet from flags on rivers, inlets or navigation channels. Vessels approaching divers-down flags closer than 300 feet in open water and 100 feet in rivers, inlets and navigation channels must slow to idle speed.
When divers are out of the water, a dive flag may not be displayed.
Most local boat captains expect divers to be where Perry was, and avoid even bringing their boats over that area. My personal opinion is that he was struck by a rental boat, or someone with a brand new boat, and new to boating in the area. Any time I see boats in the area its either the stupid Parasail boat, (beware!) rental boats that are not supposed to leave the ICW waterway but do anyway (why do they have to rent these at all, dumb idea!) and kids on jet skis. Oh and other dive boats.