I agree that the cops likely hasseled the guy a bit too much, but here's a thought. I fully support the open carry movement on the basis of protecting our Constitutional (natural) rights. On the other hand, aren't we giving the opposition a bit of an upper hand by revealing that we are armed? If the smelly stuff hits the rotating device, the bad guys may just "shoot the gun guy first". I'd kind of like my opponent to know that I'm armed only if I have to deploy it. Again, I'm not arguing for or against open carry, I'm offering a question as a tactical matter.
The other side of that coin is presentation speed. Most people can draw and get on target faster if they don't have to move a covering garment out of the way. And honestly, most people don't notice if you're openly carrying anyway.