Similarly, seasteads will trade extensively with land-based businesses. The people who profit from those relationships will encourage their government not to interfere and drive away the seasteads business.
LOL That's classic. Because the economic bolstering of doing business with a community of a couple thousand people (at most) definitely outweighs the advantage of simply blockading food from the community and then seizing all the assets.
My question is, in this modern era, why should a nation-state try to grab a floating platform?
As someone already mentioned, the amount of illegal activities going on there would be more than reason enough. Couple that with the fact that platform is 100% dependent on imports and that it is absolutely helpless to attacks, and it won't last long.
Illegal by your country's law, but what kind of a nation pays real money and resources to go and impose their law on foreign lands? And especially in this era where imperialism is pretty much frowned upon by the majority of international opinion? Only the USA will have the ability to do it and you would have to tilt the public opinion greatly.
The seasteaders are pretty sure that they will be controlling activities that can act as a magnet for attacks, like exporting drugs to countries where they are illegal and research into mass destruction weapons. That is basic common sense.