I am wondering what point you were trying to make?
Did a quickie google search for artillery firing back at shore bombarding ships. Already knowing the answer (yes they DID shoot back), I didnt look too long before I found that according to records from DDs Frankford, Doyle, and Emmons at Normandy, they were indeed shot at by light artillery and often hit.
Im going to project that if the Germans did it at Normandy, it would not be too far fetched to believe that it was standard practice in the Pacific as well.
http://www.history.navy.mil/library/online/destroyersatnormandy.htm
Note, it specifically said light artillery, not shore guns. Therefore, not only shore guns in the target hex should be shooting back, but every artillery piece in range, including mortars.
Now, I think its time to fix this hole in the game. Michael, what say you?