It is a harsh sight when a pet bird no longer wishes to eat, to speak, or to fly. No matter how well fed or taken care of, a caged bird will still desire his freedom for he will know how it felt once...even men who know nothing about freedom will chase after it...
On another note, this reminds me of the FMA delema when people said alchemy is to be used for the good of the people, for the sake of humanity- but the Headmaster does not consider himself part of humanity so why "take care of them." Is it because without a steady hand humanity will bring about it's own destruction? Should humans conceded to "I Robot Vicky's" logic: "You charge us with your safekeeping, yet despite our best efforts, your countries wage wars, you toxify your Earth and pursue ever more imaginative means of self-destruction. You cannot be trusted with your own survival."
Personally I believe being human involves suffering, but the ability to overcome those sufferings make life worth living. The Headmaster is robbing humans of this human aspect.