What a fantastic article. I've read it before and regretted not bookmarking it. Fixed that problem now.
My answer to this kind of hypothetical is very similar to the thinking many other posters have expressed here. I don't know what I'd do for sure, because I've never been in an active shooter situation.
What I THINK I would do depends entirely on the following factors, ranked by importance:
1) Is family with me?
2) What am I carrying?
3) Do I see the shooter? Do I know what's going on?
If I have family with me, we're locating the nearest exit away from gunfire and getting the heck out. Period. They are my first responsibility. If I'm being lazy that day and carrying a 5 shot revolver, I'll be encouraging others in my area to follow me and head towards the nearest exit. If I can see the shooter, am not with family and am carrying a firearm I'd be comfortable taking to a gun fight, I might try to engage
if I was certain I was dealing with a psycho murdering people and not a plain clothes officer engaging a criminal. It's another thing to keep in mind: Just because you hear shots doesn't mean you're dealing with the next mass shooter and you need to shoot on sight. If you're not sure what the situation is, you shouldn't be engaging.
Best quote from that article, IMO:
would you be willing to jeopardize everything you own and your family’s security for a total stranger? Would you be willing to lose your home, your cars, and your retirement to play Knight of the Round Table?
For me, the answer is no. My responsibility is to my family. Can't take care of my responsibilities if I'm dead or in jail, or if my assets get seized because I didn't correctly identify targets and the situation. Every law abiding citizen in Texas has the same chance I do to make the ability to protect themselves a priority by obtaining a CHL and training. I don't see why I should harm my family to make up for someone else's unwillingness to take care of their business.
I won't criticize others for making a different decision, but my family is more important to me than strangers. Sorry.