It seems Postol debunks this scenario considering the helicopter dropping the cylinder from various heights and OPCW have been caught with their pants down.
I can only assume that the engineering branch of OPCW has done the FEA calculations on both hypothesis L2-1 and L2-2 and the executive branch removed the L2-2 hypothesis calculations. Presumably the engineering branch was aware that L2-1 (the helicopter scenario) does not work, as Postol has discovered.