Bozos are always going to abound.
It's part of the human condition.
Fortunately, for me, as a firearms instructor in an agency where the off-duty weapons policies have always been very generous and accommodating, I've not felt like I've been required to justify my choices to anyone other than the head of the FTU.
Sure, I've experienced my fair share of folks who causally question my choices, when they see what I'm using in various range sessions, and ask why I'm not choosing what they're using (for all the "popular" reasons). Since I'm not in the business of shilling different makes/models of guns, I'm not someone who tries to proselytize to everyone else. If it works for them, and it's authorized, what do I care what someone else uses, right?
For the occasional "true believer" who feels like they need to make me justify why I'm not carrying what they're carrying, I've always found it simpler to just take him (or her) downrange and let them demonstrate their ability to use whatever it is they're trying to promote, doing some increasingly demanding drills.
If you can't accurately, controllably, comfortably and effectively use whatever it is you're promoting, but I'm not having any problems with my choice(s) ... and I can even borrow whatever it is you're pushing and easily run it just as well as my mine ... is it the
gun or the
owner/user that may need some attention and further work?
Every now and then I've seen someone do better with a different choice than what they're presently using (borrowing mine, for example), but I don't push them to think about changing. I let them decide that sort of thing for themselves.
It all comes down to putting accurate, controllable and intentional (and justified) rounds "downrange" in some shooting situation, and the gun is just a part of the whole process. The bullets certainly don't have an opinion about what's used to put them on the intended target.
I often end such conversations (and demonstrations) by reminding the folks that it's highly unlikely I'm ever going to be present at the scene of any future shooting incident in which they're involved. That means I won't be there to help them run their choice of equipment. It's all going to be on them. They need to make the best informed choices they can, and that's ultimately up to them. They may literally face a situation where they will have to live or die due to their choices and beliefs. The same goes for me.