...I see a very slippery slope and past evidence of sliding rapidly down this slope that makes me unable to endorse these sorts of inspections...
Perhaps...
I'm an NRA-certified instructor & coach in a variety of disciplines, including Personal Protection in the Home. I signed up with the state of Mass to be on their list of folks qualified to provide the training required for a Mass LTC. I did this with the intention of helping folks learn to shoot safely, well, and legally. There are a bunch of LTCs and FIDs out there as a direct result of my efforts. Does this make me a part of the slippery slope you mention? Perhaps...
As I look back at things I've done, I have served in the role of the "Firearms Safety Inspector" multiple times, where people invited me into their home to assess their situation, identify issues, and help resolve them. Like the Coast Guard's Vessel Safety Inspector, I was not a government agent and it was not my place to report anything to the authorities. My role was purely educational, to help people understand how to be safe, and how to comply with the rules.
I don't see a slippery slope in inviting an NRA-trained person into your home to assess your safety situation. I see it as a natural extension of the training the NRA offers now. One problem with NRA training is breaking away from your life for a day or so to take a class. Especially for a mom with kids, it can be really tough to schedule time like that. Inviting someone into your home for an hour or so is logistically much easier. I think it would remove barriers that prevent many folks from receiving any NRA training.
I don't see a safety inspection as a substitute for an NRA class. I see it as a good complement for existing training. During a safety visit, it would be easy to cover the 3 basic rules of gun safety, to be sure folks know how to tell whether their guns are loaded, and to be sure they're properly secured. It would also be a chance to educate them about further training they might choose to pursue.
You are right that NRA Training might have encouraged the state to require training to get an LTC. I can see your argument how NRA safety inspections might encourage the state to require safety inspections.
When I look at shooting tragedies in the news, where mentally disturbed or very young people got access to guns and hurt people, it occurs to me that I've intervened in situations that could have led to such tragedies. In my role as NRA instructor, I've helped folks learn how secure their guns so their kids are safe, I've taught them and their kids gun safety, and I've removed guns when the family wanted that. I always leave them with my card, in case anything comes up in the future where they have questions.
I've done all that for families that ask me, because they happen to know me. Most families have no one to ask, and it occurs to me that this might be a service the NRA and the well-qualified shooting community can offer to the broader community.
Is this me helping the country down a slippery slope? Perhaps misguided legislation might follow from this. That's a valid concern, but I'd rather err on the side of making training & safety inspections available, even if we risk legislators requiring them some day. If offering voluntary safety inspections is a good idea, then it's a good idea, even if some legislator might create a stupid law some day.
Maybe I'm wrong. Maybe there would be no demand for a Firearms Safety Inspection like this. Maybe I just happened to encounter a number of families who wanted me to do this for them, and such families are rare. If there is demand for such a service, I think it would be a nice extension of what the NRA does now. I'd volunteer as an inspector.