Two reasons I made the above statement....
1) if you had to un-conceal your handgun, the incident must be extremely serious and therefore must be reported, quickly.
2) There are 'incidents' where a 'brandishing incident' happened where the two actors went their separate ways. Attack-er called the authorities and reported an "old man drawing a gun on me at the 7-11 gas pump!" Attack-ee was arrested and held. 7-11's security cameras told the real story, and attack-er was arrested. (again, turned out to be a known suspect with outstanding warrants). Had there been no security cameras or witnesses, attackee would have been charged and attack-er would be free to attack again. Call the police, immediately!

The Meredith Emerson incident, I believe, was un-defendable (by Meredith). I suggest she was 'schmoozed' into confidence, no different than Ted Bundy's victims. So, carrying a weapon won't protect you from being 'sniped' or 'con'd'. Would she have been justified to use deadly force? No. Right up until she turned her back, then it was to late.

If you fear for your life, you may use any force up to deadly force. It's an option. A civilian and LEO have a different set of criteria in which to decide. A civilian isn't an "officer of the court" or "professional witness of the state". A civilian's only available action is to 'defend' themselves.
The mantra, "When seconds count, help is only minutes away.", is the thinking behind civilian deadly force.