It wasn't a Hijack, it was an unlawful interference with an aircraft. The Swiss are talking about charging him with 200+ counts of kidnapping.
These are acts or attempted acts such as to jeopardize the safety of civil aviation, including but not limited to:
• unlawful seizure of aircraft,
• destruction of an aircraft in service,
• hostage-taking on board aircraft or on aerodromes,
• forcible intrusion on board an aircraft, at an airport or on the premises of an aeronautical facility,
• introduction on board an aircraft or at an airport of a weapon or hazardous device or material intended for criminal purposes,
• use of an aircraft in service for the purpose of causing death, serious bodily injury, or serious damage to property or the environment,
• communication of false information such as to jeopardize the safety of an aircraft in flight or on the ground, of passengers, crew, ground personnel or the general public, at an airport or on the premises of a civil aviation facility.
Definition Source
ICAO (2011), Official definition, Annex 17 (Security)