Given the situation I would lawyer up as well. I'm completely unattached to the shooting and if I was asked to come in regarding it, it would be with an atty at my hip. And I hate atty's

In ref to the 500ish yard handgun shot being a 50/50 success, pass what you're smoking because it must be the good stuff

You can't compare a handgun hunter with the proper equipment, placement and frame of mind to someone with a 4" semi auto being shot at in a crowd of panic from an unknown position.
The right gun, the right person, and at the right place in time makes a world of difference. Just being in a position to put pressure on a shooter will save lives as a killer now has to address a threat. No killer is looking for a fight and they're generally not prepared for one.
None of those factors are present in that crowd. At best you have an ineffective round getting shot 'over there'. Put a handgun outside his room though, different story.
I recently learned that NFL games employ a professional sniper in an elevated position watching the crowd. I'm guessing concerts will start doing the same soon.