The Royal Thai Navy is pursuing local woman Supranee Thepdet and her gringo spouse Chad Andrew Elwartowski for aggression against Section 119 of Criminal Code involving:
any acts that cause the country or parts of it to fall under the sovereignty of a foreign state or deterioration of the state's independence (archived)
The couple is alleged to be plotting the birth of new nation on their 6 meter wide floating platform parked outside of Thai territorial waters yet within a portion of the Thai Exclusive Economic Zone the Thais claim is a critical route taken by oil tankers on their way Phuket. Thai law offers sentences of death or life imprisonment for violations of Section 119.
The couple are not defending the sovereignty of their offshore "seasteading" platform. Beyond what they aren't doing their location is unknown.