It's one of those things, TSP. We're not a protected class, and (I'm not trying to make a 2A rabblerouse here) most people just view it as "leave your gun at home". It's just a thing you can either bring or not bring, not a question of how we identify ourselves.

What's not understood is that for a lot of gun-folk, it's exactly that. I can no more change my identity as a "gun person" than I can cease to be male, or a sarcastic smart-***. Shooting and shooting sports are too connected to how I think about myself. If a lot of your favorite memories growing up involve firearms, you can't simply choose to erase them. So many of Same thing comes up periodically on other forums: "I'm dating this girl, but she hates the fact that I own guns, and doesn't want me to carry or have them around". Then she doesn't like you, dude, she likes the version of you she wants to create.

So if someone were to claim the practice is discriminatory, non-gun-folk (and a pretty hefty portion of gun owners, I bet) would dismiss them as whackjobs, when discrimination is exactly what it feels like. That's why when you enact a law that criminalizes law-abiding gun owners, people react strongly--because you've hurt them, and you've made it personal.

Also, the above argument about identity has a pretty high success rate when talking with regular folks and mildly anti-gun types.