The chance of fuel burning from a fully enclosed marine fuel tank is virtually zero. The environment is more than capable of handling that volume of fuel oil on its own. If the diesel ever makes it to the surface most will simply evaporate.

If you are ever near a boat fire. The moment plastic or fiberglass is starting to burn the fight for the boat is over. You must leave with zero delay for a long list of reason. The fumes are always toxic and evacuation upwind is the key.

Once a pleasure vessel reaches the point where the fiberglass and plastics are burning there is little chance of saving anything. The combination of burning plastic fueled by the oxygen in the wind will burn the vessel to the water line.

Any talk of "clean up" is PR, locals hunting for contracts or lawsuit damages, or simply nonsense talk. The diesel came from the earth and the earth will take it back.

Yes a skilled diver can go down with suction hose from a pump and move the fuel along with large amounts of salt water. Once you have that contaminated fuel in drums located in the VI. What would come of those many gallons of contaminated water and fuel oil? The fuel is best left where it is. Sometimes towing/dragging the wreck to deeper water can be a plus.