Has taken a while to answer this as it is a good point. Pretty much all people in the diving community care about other divers. None of us want the reputation of diving killing people.
I do care about people. In the case of the incident I wrote about, the guy's kit was horrible; a cobbled-together Frankenstein rig that was the antithesis of the DIR rig I was diving. However, I do see other types of rigs on my travels, for example these two which have thousands of dives on them. It's really not about the rig, but about the way it's used. Similarly people's gas choices where, unlike the snobbery frequenting these boards, many people still use deep air.
So, what can you do? And where would you draw the line?
Diving is not about enforcing particular configs. Although maybe that's the case for some people
Diving is about diving and learning how to dive in your environment.
In essence, if "I" consider your rig to be unconventional, what gives "me" the right to interrogate you about it? I’m not special constable Wibble of the dive police, nor blessed with 20/20 foresight. I'm just a diver who's paid for my space and am looking forwards to a dive.
Generally, it's not about the kit config, it's about the way that person dives.
I guess if I was to rock up at some random location for a dive boat, I'd be expecting to follow their rules. I'm unlikely to choose a "recreational" boat as I want a long, peaceful and enjoyable dive away from other people. Technical boats are different. You don't book on them unless you've the experience to do their planned dives. Am pretty certain that should someone rock up for a 60m/200ft dive with a single ali80 and no deco stages that the person would be quickly dealt with.
As with everything, there's degrees of crappyness. At one extreme there's the OW kit for a deep technical dive which is obviously wrong -- that dive is just not possible on a single. But what about the cobbled-together doubles rig with a back-mounted decompression cylinder and multiple second stages? That's not a great look but it's perfectly diveable given the right skills and experience. Similarly gas choices.
In the end, it's the skills that kills. Skills include planning, practice and experience. Those are really difficult to determine unless you want to do an assessment dive with someone.
This, in spades.