I do find a flaw in that logic. International waters are not and should not be under anyone's authority. The system the US implements, like the one which proceeded it, is a fundamentally decentralized system. The US guarantees free navigation, but there's nothing stopping any other nation from doing so as well. China could, Russia could, Guinea-Bissau could. Indeed, the US is not the only nation engaged in anti-piracy operations. You don't need the US to act in good faith, the system is stable in that every country doing what is in their own best interest is also in everyone else's best interest. Really, every nation should independently guarantee free navigation, but luckily that is unnecessary.
In practice the US has such an immense navy that while it guarantees free navigation there is no real need for other nations to, and if it were to oppose free navigation there is no navy that could stop it, so at the moment the US de facto decides if free navigation is guaranteed, but there is nothing de jure entrenching the US in that position - should it ever derelict its duties or otherwise grow weak there is nothing stopping another nation, or group of nations, from taking up the mantle.
On the other hand if an international body were to be set up to do the job, then we become totally reliant on its efficacy. It's impossible to have a truly independent organization - the people who compose it, as well as the people who provide material resources to it, are not independent and unbiased - and unlike a nation which benefits from the trade it protects, this organization's only incentive would be to appease its backers. Even if it avoided malicious corruption, it would fundamentally entrench the geopolitical status quo, and getting everyone to agree to remove it may be impossible even if it strays woefully far from its mission.
The US's position may rub a lot of people the wrong way, they see the US as being some sort of self-appointed overlord and fear if it has nefarious intent. They fail to realize the level of gross indifference that the US has towards the larger world. We just want to be able to import cheap crap, any benefit to other nations is purely ancillary, and we will continue on our course for precisely as long as it is the easiest way of maintaining our steady supply of cheap crap.
In practice the US has such an immense navy that while it guarantees free navigation there is no real need for other nations to, and if it were to oppose free navigation there is no navy that could stop it, so at the moment the US de facto decides if free navigation is guaranteed, but there is nothing de jure entrenching the US in that position - should it ever derelict its duties or otherwise grow weak there is nothing stopping another nation, or group of nations, from taking up the mantle.
On the other hand if an international body were to be set up to do the job, then we become totally reliant on its efficacy. It's impossible to have a truly independent organization - the people who compose it, as well as the people who provide material resources to it, are not independent and unbiased - and unlike a nation which benefits from the trade it protects, this organization's only incentive would be to appease its backers. Even if it avoided malicious corruption, it would fundamentally entrench the geopolitical status quo, and getting everyone to agree to remove it may be impossible even if it strays woefully far from its mission.
The US's position may rub a lot of people the wrong way, they see the US as being some sort of self-appointed overlord and fear if it has nefarious intent. They fail to realize the level of gross indifference that the US has towards the larger world. We just want to be able to import cheap crap, any benefit to other nations is purely ancillary, and we will continue on our course for precisely as long as it is the easiest way of maintaining our steady supply of cheap crap.