I'm not, and I dam sure practice and train more than 99.9% of the police ever think about.
Since none of us were there, it is hard to say if any individual could have done anything, some said he was only a couple of feet away, and perhaps someone could have done something, but no one did, had there been an armed defender there may have been a chance, or they could have gotten tagged in the first volley of fire.
There are those that say no one could have done anything, and those that say they could have stopped the guy, but since none of us were there, none of us know.
Too many variables, to consider to "know" what one would have or wouldn't have done. but that said we saw the senior citizen stop the armed robbery at the internet cafe, and it was his willingness to engage, that made the difference.