It's just not fair to them to shoot at them with big bad evil scary guns. We should just let them have their way and rape our ships.
Far less simple than the mindset which is present in anti-gun restrictions at home.
Insurance policies limit what people can and cannot do. Violating the policy can void the insurance claim. If you resist pirates and that is against the terms of the insurance then any and all damage is not covered by them. Additionaly they can drop all coverage of you, and in many lines of work and business you need insurance to have a license and legaly operate.
So lose your insurance, and you lose your ability to even operate.
So insurance policies are extremely powerful.
Insurance companies look at everyone as numbers. Certain actions give more predictable numbers than others.
Self defense could result in no damage, no hostage taking, and even reduce the amount of future piracy. It could also result in an expensive hole from an rpg in the side of the ship, paid for by the insurance company.
Currently surrendering to the pirates causes no damage to the ships, making insurance liable for no damage. Whether anyone is harmed, or other things take place matters less than the numbers. They are not insuring crew lives, they are insuring the ship.
Whether people or businesses are secure in thier property matters far less.
Further, many of the restrictions on arms are due to internationly imposed restrictions on small arms.
Restrictions produced in the UN, EU, and by various agreements between rulers of peasants throughout the world.
The US government itself is a very active participant in working to curb the flow of arms to mere common people. The premise is often to keep them out of the hands of criminals, terrorists etc
In reality it is just to make various regions of the world easier to control, both by thier own governments or invading occupying forces.
Disarmed populations are easier to control with armed forces.
(Our own ITAR system has been abused to include small arms export restrictions. Restrictions then enforced by agencies such as the ATF. Restrictions in place to keep small arms from leaving America and going to regular peasants, who may resist tyranny.)
The laws imposed to that effect end up impacting many segments of the international community. Including shipping in international waters.
This may actualy lead to the UN and similar bodies imposing more laws and projecting more control over the seas and oceans. Creating international law outside of national borders that will set a precedent for restricting you and I even in international waters.
So this could become a great way for the UN to establish that it sets binding laws even in international waters on all matters. The type of laws that could eventualy make it illegal for you to exit US territorial waters with "small arms" and enter international controlled waters.
Currently it is illegal to export without going through an official process already. So leaving the waters to go to a nation without declaring the firearms and taking the legal steps is already restricted by relatively recent restrictions.
However such UN changes could make it illegal to even go fishing at sea in international waters with small arms.
Laws that can then be enforced by our very own Coast Guard (now part of the Dpartment of Homeland Security) if they find you in violation.
Antis have had some trouble quickly removing our rights through our legal system. Removing them through international pressures and treaties though may be much more effective.
Rulers do not like commoners with small arms, period. So international support always will exist, and always has existed. Rulers are in agreement that the peasants should not have items which could harm thier armed forces.
It has just not been feasible to implement such legislation before the structured global government network we have now.