Totally disagree. For the vast majority of software dev jobs (like 98% of them), you just want someone who shows up and does the work without making much of a fuss. People who openly demonstrate that they are difficult to work with are freely signaling "do not hire me, I will make your life much harder"
Why would you hire someone like that? You'd much rather have someone who is 50% as skilled but gets along with everyone and doesn't make other's lives harder because of their personality
For the vast majority of people who post stuff like that on their blog, they show up and do the work without making much of a fuss.
I know because I've worked with several of them.
And you'd have no problem with your coworkers always keeping a gun on them? This seems like a recipe for a workplace incident
But sure, the workplace will usually have a policy about guns, and that's more an HR problem than a problem for me as an interviewer. And I'd put the burden on him to enquire about that aspect.
But (depending on where you live) you'd also be surprised how many coworkers carry guns with them. At one company I was shocked. HR put a policy prohibiting concealed carry, and damn near 80% of my team took serious issue with it. It felt like I had accidentally walked into an NRA meeting or something. There were never any issues, and we tended to get into some heated arguments at that place. Turns out most gun carriers recognize and respect the gun and don't just pull it out and start shooting people every time they get offended.
Frankly, I think if people won't hire because of a post like this, then the interviewers are the one contributing to the problem.