Open carry or concealed depends upon what I'm wearing, at the time. If I'm wearing a suit as I do for work, my weapon is generally hidden by my jacket. If I'm wearing slacks and a shirt, my holster will be visible. I've carried most of my adult life and rarely had anyone taken aback by it. I believe a lot depends on how you carry yourself and how you are dressed. As you mentioned above, you thought the guy was an odd duck before you knew he had a weapon.
Now here, within the county, chances are pretty good that I know the owner or manager of the establishment. That is the advantage of a small town. Our neighbor's version of George Zimmerman drives a four wheel drive red and black golf cart. He's that odd duck that you talk about. Late sixties, bearded, ball cap… Usually carrying a .45 caliber revolver in a very low western style holster. He's got a walking stick and one of those multi cell black flashlights, not the new LED type but the old seriously heavy ones. He's legal, he has a GCL and has attended training not only in firearms but paramedics, too. Big difference between him and Zimmerman? He calls for both LEO back up and neighborhood back up. He says he's not a hero.