Originally Posted by
Basil
I. The captain, or Pilot in Command, is not 'in charge' of the aircraft; the captain is 'in command' of the aircraft.
2. The despatcher (or whatever the person in charge of boarding is known) is responsible for the boarding process.
Given that the captain apparently has discretion as to whether to fly with specific passengers, it is not obvious that there is no responsibility as well.
A trial would certainly clarify these responsibilities, but that may be very unpleasant for some of the individuals involved.