I would find it hilarious to wear something similar just to troll.* I would also loudly interrupt the instructor every time they start going off on their tangential, 'really experienced themselves,' stories about how if they'd been ready to handle things like I was, they wouldn't have had the experience with their gun that they had.
*I've been to some of these classes. They are almost universally taught by someone with a mentality probably exactly along the lines of the dude pictured, but with some social awareness that told them people would be watching them too closely... and they love to tell 'their' stories about when they had to use or display their gun. I always did the smart thing and kept my head down and try to ignore the rednecks/tacticool operators fantasizing about shooting whatever flavor of humanity they looked down on.