The capture of a huge car carrier is a bad news for everybody, we don't know the particulars of the hijacking, maybe the ship was obliged to stop under the threat of RPG. A rocket can enter very easily the upper decks because the plates are generally light also to prevent the weight of the constuction at high levels; once inside, a rocket can devastate the ship giving origin to a huge fire of cars very difficult to extinguish. The speed of this ship can reach easily 18 to 20 knots and the manouvreability in open seas is excellent. The watertight doors of access to the lower part of the ship are generally located on main deck close to the gangways and pilot boarding areas, bunker embarkations (normally closed and flat), fore and aft mooring stations. All these doors should be kept closed and locked with keys and security device (cleats, bars...) which allow the opening only from inside in order to not contrast with safety. Probably a door was left open or was forced with explosive. Now it will be interesting to see how the pirates will manage the possibility to take the cargo onboard. For sure some hundreds (even thousands) of cars could be very useful to get money in African countries where no governments or laws are in force. Think also just to the value of the optionals of the cars...
For sure something must change, let's say that it is impossible to stay at more than 600 miles from shore without a support, no fishermen go at such distances for their job. So it would be normal to catch all boats and suspects found in the area without reason.