The point of seasteading is you do not flag your ship under any nation whose jurisdiction you are seeking to evade. To be unflagged is to be boarded by any nat

The point of seasteading is you do not flag your ship under any nation whose jurisdiction you are seeking to evade. To be unflagged is to be boarded by any nation's ships as a pirate vessel, so you use a flag of convenience, like Panama, Liberia, Malta, Cyprus, Marshall Islands, or even landlocked nations like Mongolia--anyone whose navy is unlikely to find and board your vessel, and who will not seek to enforce laws regarding crew and passenger safety or conduct. The only interest the US is likely to have in this is specifically with the US citizen, not the Thai citizen or the vessel. So the US State Department, which is already involved as much as it cares to be involved. If anyone in the US executive cared about such things, the US ambassador or a consul might mention that if Thailand does not keep to the LoST, the US would be less inclined to support the right of free navigation for Thai oceangoing vessels that may have cause to transit the South China Sea. And this would disappear right quick. A glorified fishing bobber with two people living on it does not make a Sealand situation.