Yes, the queen dictates the mood of the hive but it happens in 2 ways- her genetics, and her pheromones. It can take over a month before the mood of the hive would change after a re-queening. Even with a queen replacement, there are thousands of these aggressive bees already in there. With nearby kids and horses, and the incredible behavior of this hive, I don't blame him for deciding that the responsible step is euthanizing the whole colony.