Guy deliberately fans back his coat and grips a holstered handgun.
That is definitely brandishing and is a punishable offense.
Class 1 misdemeanor. If that Best Buy was within 1000' of a school, class 6 Felony.
I would have tried to get his license plate number and reported the incident, even if the cops "can't do anything because we didn't see it happen" as I've been often told.