Yes, yes, I know it's easy to say these things: but didn't the heroes of Flight 93 teach us anything? As the cliche goes—and like most cliches. It's true—none of us knows what he'd do in a dire situation like that. I hope, however, that if I thought I was going to die anyway, I'd at least take a run at the guy.
I do agree with Ana Marie Cox's take: "Better yet, just jump him." Or, best yet: you could always try the ol', "Shoe's untied!" bit. Works with my theoretical mass shooting murderers all the time."
Derby goes down at the NRO as a big time thinker...I love these fools that take a crazy situation and imagine how they would save the day...He suffers from some insane Hero/myth pathology.
UPDATE: As John notes: There was acts of pure bravery throughout the whole-tragic-event...