Also, it wasn't a "merchant ship" that the Hornet encountered but a fishing boat
As was the custom then fishing crews used had their families on board on deep sea trips. I remember an American sailor descibing the screams of the children as machine guns tore though their vessel. It was totally unnessary, the boats did not have radio but because of them the B25s were launched far too early which caused all the range problems.
Such is war.