You can't know what you will or will not do, until the time and conditions present themselves.
Pretty much true.
I have killed downed but still live deer in less than half a second with 5" bladed knife- and this was before I had years of training. I'm sure that deer hit with a crossbow bolt was in better shape than this poor soldier after being struck by a car, too.
Very true as well. As soon as that guy was hit by the car, he was most likely done. Those jerks were on a mission.
There is no real way to know how the presence of armed citizens would have affected this particular outcome. Monday morning quarterbacking is just that, after the fact. You can make some generalizations, such as:
If there were a well intentioned, armed citizen there, then the response time would surely have been faster than 20 minutes. That being said, I doubt that would have saved the life of that soldier. It appears the attack happened extremely rapidly, and would have been inside the decision cycle of anyone who may have been in a position to help.
A pistol is not a talisman that prevents or stops all bad things from happening, but it is a tool that gives you more options. If some homicidal nut has a gun pointed right at your head demanding money or whatever, and you want to try to draw from deep concealment and tag him, good luck with that. But in this particular case, if those nuts had decided to continue killing other people after killing that soldier, someones pistol could make a difference. Every situation is different, and you can't predict everything.
The point I believe many are trying to make, is that having armed citizens, in general, is a deterrent, and can help save lives against potential agressors. Maybe not in EVERY case, but that's true for all things.
I think another thing that bothers folks is the percieved apathy, at least initially, of the people near the scene of that murder. Maybe that is an incorrect assesment. Maybe everyone around DID try to run for help or whatever, or maybe even threw rocks at the attackers, for all I know. I certainly HOPE they did more than simply film the event. If that's the case, then that's pretty lame, and a sad testament to us in general.