Could be the old smoke n mirrors act. The execs buy a few shares, makes the investors think 'well if the execs are buying and are confident in the product it must be a good investment', hence they continue the game. The reality is the execs have only bought small parcels, and even if the share price tanks lower it doesn't matter as they are all going to hit paydirt when a buyer comes in and snaps up the airline.
It's all a game whatever the execs do, a game designed to male themselves excessively wealthy at the behest of anyone or anybody else.