This is such an excellent point you make. If the victims had been attacked in their homes (or even in public) by someone who singled them out for a personal vendetta, that would be a private matter. If the victims had been killed in an accident of some kind--plane crash, building collapse, car accident, poison gas from a refinery, etc.--then it would be a private matter. But those terrorists didn't care who they killed. It could have been literally anyone in the world inside those towers that day, and they all would have been the target.
I don't care how the victims families have reacted to this tragedy. If any one of them wishes to forgive the murderers and just "move on," that's just great. Good for them. But it isn't their place to forgive them on my behalf, because the next victim of these thugs may be someone I love. And I can assure you I would not forgive. Ever.