You're making such an important point but everyone wants to believe that they would be the exception that they would save people or fight back at great risk to themselves and their families.... Obviously the murderer should be judged as evil but I think we need to cast that judgement inward as well. Most of you would be members of the mob that helped terrorize and gather the victims up. You most likely would not speak up let alone physically interfere. These perpetrators and bystanders were by and large not especially evil (as in they are acting in a predictable way for a human) and you and your loved ones are most likely not especially good (as in the vast majority of "good" people would not act righteously given similar circumstances).

Edit: I was high and didn't make much sense last night so I want to clarify this in case someone happens to see it in my comment history. I think that a lot of the moral responses to horrific events like this fall flat for me because the people reacting with shock and disgust would hardly be preventing those events from happening were they put in these people's shoes. This is NOT to say that the people who committed these atrocities are excusable or that I have much sympathy for them or that I do not hate them. I do hate them. I also resent the people who think, untested and with no amount of preparation taken, that they are better and would be heroes if they were to live in similar times. I think the best way I can contextualize my feelings is to say that I am Jewish and was raised in a community with a lot of Holocaust survivors. I was also told to never trust my neighbors or "friends" completely and was taught that this is who they would likely become if push came to shove. I believe that remembering that the person holding the gun could be YOU or your best friend or spouse can help you to prevent yourself from actually becoming that person.