Jesus, what huge thread of indecision! If the facts are as stated, this guy should have been arrested by Service Police (there would have been a power to detain) and handed over to civil police who properly should have interviewed/charged/released as appropriate. The aircraft could have then been released subject to appropriate measures being put in place, and an agrreement to meet all charges. The fact that the aircraft is US registered is of little consequence, but to list the possible offences that the CAA Enforcement Branch might want to consider would fill several pages. That said, always two sides to a story....