I absolutely agree with you. Most cops on the side of the road equate the firearms purchaser ID with an Owners ID and would likely turn someone loose if they provide it versus someone who didn't have it. That said, if you are transporting within the exemptions is it not required. It is required to buy long guns and ammunition that can be used in handguns. You can buy a handgun with a permit to purchase a pistol and not even check the box to obtain the Purchaser ID at the same time.
Would locks go towards intention? Yes. All of the things you said cannot hurt. I suggest that people who move to NJ get their purchaser ID but it is not a requirement to own or transporting their NJ legal firearms that were purchased in other jurisdictions or inherited. Registration in NJ is voluntary for guns purchased elsewhere and I never recommend anyone actually do it. Handguns purchased in NJ are registered on the Pistol Permit.
There is also no duty to inform in NJ. Don't lie to an officer but don't volunteer it either and avoid the issue entirely. It's also a good idea not to draw attention to yourself if you're transporting firearms.
I fully admit to being a little over-the-top.