What’s happened here, I think, is something awfully mundane.
Sometimes this sort of behavior gets seen by parents of children in distress, especially if they’ll able to pay close attention to their children as they develop and react to stress. Early age children’s school teachers have way more opportunities to see this phenomenon at work.
A child will tell such a story not for its informational value but for safety: to ensure attention in hopes of obtaining responses that signify acceptance or wariness or respect.
Consider a child new to a school due to a family move or parents recently divorcing, some major change in living circumstances that strikes at the child’s sense of personal security and social standing. For example, a teacher says something to a child relatively new to the class, in front of the child’s classmates, that’s something like encouraging praise - I really like how you played the part of the fiddler at the barn dance, it’s like you actually were playing, have you taken music lessons - which to teachers is a MEANS by which they can test for the child’s sense of self, but to the child contains an opening to impress everyone present - and the child will grab at the ‘lessons’ part of what the teacher said and say something like, Yes, I’ve been taking lessons for a long time.
It’s not a HURTFUL lie, it’s a RELEVATORY lie. Someone telling such a story has an exaggerated need to control social standing and command respect. To the child who says it, it holds the promise of increasing the chances of someone the child is trying to impress - a teacher, a parent, a young friend from school (but never a brother or sister, especially not a twin or older sibling - all of those will be considered too skilled at detecting and picking apart bullshit).
Beyond that, it’s more difficult to conjecture more precisely on the particular need Carson felt at the time that led to him saying this. I think it’s REASONABLE to suggest Carson perceived the questioner’s skepticism towards his broad prescriptive panacea of an unarmed grouping of people who may not even know each other rushing a young man none of them know menacing them with assault weapons and saying threats, issuing orders and demands, and saying all manner of unfamiliar things aimed at promoting disorientation and fear And on feeling that skepticism, Doctor Carson resorted to saying soothing things framed as personal anecdote to ASSURE the listener, Oh yes, listen to the doctor, he knows what he’s talking about, he’s TRIED THIS OUT.
Ben Carson has a personal insecurity problem that, with all due respect, is somewhere between that of a frightened child and President Richard M. Nixon.