IMO, the Chancellor's reaction was reasonable, appropriate, and ethical. She well understands the damage Osama Bin Laden and Al Qaeda have inflicted on Western interests, including those of Germany, including the human toll. She well understands the continuing threat Al Qaeda posed to civilians, German and non-German alike. She well understands the significant shared interest of countries, including Germany, in depriving Al Qaeda of its iconic leader and commander in chief.
If anything, her sentiments represent the more ethical message. She expressed relief that an individual responsible for massive bloodshed, the dissemination of hate, and one who almost certainly continued to plot more attacks, has been neutralized. That he is no longer in a position to inflict harm is good news except by the most novel interpretations. In contrast, those who so eagerly criticize her don't even attempt to come to grips what a world in which Osama Bin Laden were free to continue to carry out his activities and ambitions would really be like.