There are two possible explanations:
1. Criminal negligence by the Captain and crew of the destroyer.
2. The container ship's erratic course prior to striking the destroyer could indicate the container ship was stalking the destroyer. To successfully stalk the destroyer, the container ship would have had to have had radar cloaking equipment, and the purpose of this attack was to test the effectiveness of this radar cloaking equipment against a U.S. warship. If so, the attack was successful, and their radar cloaking equipment has been proven effective against our warships.
That said, an Aegis destroyer Captain is not unprepared for such as this.
And there is no chance, given the radar capacity of the USS Fitz, that this was an accident.