My position is he was free to make whatever decision he wished in this as there were no legal prohibitions (that we know of) to forbid him doing as he did.
I would suggest you consider there was no prohibition for him to have done what he did, not in Law, Regulation, or Policy.
More learned folks might disagree.
FAR Part §91.9 Civil aircraft flight manual, marking, and placard requirements.
(a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without
complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual,
markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.
(b) No person may operate a U.S.-registered civil aircraft—
(1) For which an Airplane or Rotorcraft Flight Manual is required by §21.5 of this chapter unless there is
available in the aircraft a current, approved Airplane or Rotorcraft Flight Manual.
FLIGHT MANUAL AS 350 B3 Arriel 2B1 EASA APPROVED
SECTION 2
LIMITATIONS
2.1.1 TYPE OF OPERATIONS
The helicopter is approved to operate :
- by day in VFR.
- by night in VFR, when the additional equipment required by
operational regulations are installed and serviceable.
The following are forbidden :
- Aerobatic maneuvers.
- Leave the aircraft with no pilot at the controls while rotor is
spinning.
- Flight in freezing rain or icing conditions.
- (visible moisture and temperatures conducive to producing ice).
- In flight engine power reduction using twist grip control except for
engine failure training, emergency procedures referring to it, or for
a technical flight.
2.1.2 OCCUPANTS
- Minimum flight crew ................. : One pilot in right seat.
- Maximum number of occupants
(including flight crew)................ : Six