The point was that blowing up the plane before it landed carried the least amount of risk, that one death could prevent the death of thousands. There was no possible escape for the zombie bees as they would have all died in a fiery explosion. Landing the plane or opening one of the doors do jump out means that the bees have a chance to escape and start zombifying the world. Also it was aired on mothers day on purpose, the episode where Alexander dies was also aired on the anniversary of his death.