I'm going to go out on a limb here and guess that most of the people who think this gentleman is "our own worst enemy" live in states where it isn't legal or very common, which isn't bad, and doesn't mean it's right or wrong. We are all entitled to our own opinions.
In Utah, where I used to live, it was more common on a day to day basis to NOT see someone open carry. It was/is the norm there. Where I now reside, and almost have for 5yrs, I don't believe I've seen one person open carry, even though it is legal to do so. That seems weird to me!
If more people were seen open carrying, those not accustomed to it (gun enthusiasts or not) might feel a little uncomfortable at first, but as time goes by and they see that those open carrying aren't a threat (and aren't shooting up the place) will begin to relax, and a new norm can be established.
I don't think this guy did anything wrong, and I think more people should open carry to make it a norm. That being said, I am grateful to live in a country where we are able to have and share our own opinions, and maybe even change some of those opinions that others have, or our own.